88GMCtruck's never ending 88 GMC build thread

Time for another build thread! I have enjoyed the other build threads I have kept: the 78 Nomad trailer resto, and the 99 6.5L Towpig. Since the towpig is history, I'm concentrating on the 88 once again. Seeing as I have never kept a running build thread, I have decided it is time to actually make a build thread about my truck to document some of the progress, etc. Plus it's an excuse to post little updates that wouldn't otherwise be reason for a thread themselves.

We'll start with it's history. Grandparents bought the truck in 1988 brand new. It's a regular stepside K1500 350/700R4 truck in top of the line SLE Sierra trim inside and out. An off note, in 1988 the Z71 package didn't exist and the truck for whatever reason did not come with towhooks. What made the truck interesting is the RPO "Super Saver Package" that kept the truck as a SLE Sierra but stripped the interior down to the essentials: basic bench, AM/FM, AC and cruise. No tilt, no PWDL. In 2002 I received the truck with 88k on it (ironci!?).

But it being stock didn't last long.

Being 16 the truck underwent many changes, a good amount of them cheap, free or made up by me being I couldn't afford much. A few were learning experiences, some stayed with the truck, and of course there were a few I am no longer proud of (such as altezza taillights and blue neon).

Due to the miles/age of the truck, I replaced lots of small things, waterpump, radiator, alternator twice, starter a few more times, etc. Eventually larger things like the rear end went out, and a few years later the 700R4 gave up the ghost. By 2005 I was in college and the truck IMO was looking pretty good.

Seeing as I lived in a very snowy climate at college, I also picked up a winter set of wheels that also served as a good wheelin set.

At this point the truck ate through a second 10-bolt and the addition of a 14SF was added. I always was into 4x4ing and my truck, so there was already tons of ideas in my head. Eventually I started making good money in the summers and in 2008 I picked up the 02 GMC. The front suspension in the 88 at this time needed a full overhaul, so about a week after owning the new truck I decided that rebuilding the suspension meant it was time to install a Dana 44 front axle. The parts collection began. A little cut here, a grind over there and a few welds resulted in 3 hard weeks working with my dad as much as humanly possible between work and sleep to convert this thing.

The result was 8" of lift while still being a very streetable, yet capable truck. Build: http://www.fullsizechevy.com/forum/...ions/336282-88gmctrucks-sas-build-thread.html

After a good deal of wheeling and driving later, this happened.

The Automatic didn't like it very much but it survived another 6 months. Then came cablights and stock mirrors sometime in 2009

My previous water incident ended up prompting this upgrade.

The summer of 2010 I bought a 1978 trailer for camping. It's been a project all in it's own. Build: http://www.fullsizechevy.com/forum/...ler-restoration-project-88gmctruck-again.html After towing it awhile, I finally did a much needed gear upgrade from 3.73s to 4.56s.

The 88 took a year long break from most use when I bought a 99 6.5L K2500 5-speed truck. Build: http://www.fullsizechevy.com/forum/...78-88gmctrucks-99-6-5l-towpig-slow-build.html

But in the end I sold it and am once again concentrating on this truck. I just finished converting the truck to 8-lug with hubs up front and a detroit locked SRW Corporate 14FF axle from a CUCV.

Next plans include a repower. The stock TBI350 is entirely original and is just about to roll 200k. It burns no oil and has great compression still, just lacking in the power department.
Last edited:
Mar 22, 2011
Re: 88GMCtruck's never ending 88 GMC build thread

im drooling while in class seeing this thread. i cant wait for more. you have given me so many ideas for my own truck and some friends trucks too with your various threads. thank you lol
Re: 88GMCtruck's never ending 88 GMC build thread

Have you ever counted how many sets of wheels that thing has had on it?
Wheels and Mirrors....

16x7 Stock GM 6-spoke aluminum on 265/75R16
16x8 MHT polished aluminum 6-hole on 265/75R16
15x10 American Racing machined 12-hole modular style on 33x12.5R15 Studs
18x9 ASA RS4 Chrome 7 spoke on 285/60R18
16x7 GM polished GMT800 Yukon wheels on 265/75R16
16x8 Eagle Alloy polished D-hole style on 285/75R16
16x8 Raceline Renegade Polished on 315/75R16
16x8 Eagle Alloy 589 Polished on 285/75R16

GM stainless (stock)
GM black sport mirrors
Back to GM stainless (stock)
CIPA extendable stainless stock style mirrors
GMT800 towing mirrors
GM black 95+ mirrors
Back to GMT800 towing mirrors

im drooling while in class seeing this thread. i cant wait for more. you have given me so many ideas for my own truck and some friends trucks too with your various threads. thank you lol
I was following your 2500 thread and was always curious about the 88. Thanks for posting this.
No problem guys, thanks. It's about time I have a thread for it.


New member
Apr 17, 2008
Bangor, ME
Re: 88GMCtruck's never ending 88 GMC build thread

They look like the altimeter and angle gauge pod my buddy had from the factory in his 4 Runner. I don't believe GM ever offered these.
Re: 88GMCtruck's never ending 88 GMC build thread

What are those gauge on your dash? Are they some kind of option that these trucks came with?
They look like the altimeter and angle gauge pod my buddy had from the factory in his 4 Runner. I don't believe GM ever offered these.
They are from a japanese spec nissan pathfinder. They fit the dash of these trucks well, and that is it's actual color, not repainted. It had an altimeter I removed and put a transmission temp gauge in it's place.
Re: 88GMCtruck's never ending 88 GMC build thread

Have had a busy week! Lots of things going on at work, and on the project front for me.

Well, the answer to my motor swap came a bit quicker than expected....

Motor came into a friend's junkyard.... 1990 TBI 454 with 76k on it. Motor compression tested 160PSI in all cylinders. It'll be pulled soon and will be going into the 88 in a few weeks. Along with that the transmission is getting a freshening up, and new exhaust will be in the works as well.

I did do a bit of work on it. Saturday I pulled the pinion & carrier and put new bearings in it. Super easy job, had everything apart in 30 mins. :D After re-installing, I gutted the passenger door and put a new door on the truck. Color is a bit more faded, but it's better than dented.

I also picked up another project this weekend.... 3 Suzuki LT250R quads, complete with a metric ton of spare parts.
Re: 88GMCtruck's never ending 88 GMC build thread

It's time. Well, almost time.

Picked it up last Sunday. Well, actually pulled it, but yeah. 1990 Chassis Cab 454 TBI with 76k on it. I even got to drive the donor truck. Looks a little rough, but it was actually spotless inside and the motor was WELL taken care of. Fluids looks proper, and the filters were all wix brand. Here she is. I have the motor with all the accessories, harness, ECM, 34" radiator and shroud.

While I was up at the yard the tires got switched around. 35s are back in place, now she looks proper again.

And put the 6-lug Racelines on the 285/75R16 Cooper ST, likely will be going on the yellow truck tonight.
Re: 88GMCtruck's never ending 88 GMC build thread

Just a bit of an update. Had a party this past weekend, haven't done much in the way of truck work. I have been researching on it though.

Turns out, the motor isn't what I thought it was. Being the truck was a 1990, it has the steel accessory brackets, spreadbore intake and TBI adapter, but should have had stamped steel valve covers.... A 1990 was a Mark IV motor.

The aluminum covers threw me. So after pulling a valve cover, researching the casting numbers on the heads and block it turns out this a a Gen IV L19 service replacement block. Which means it has a good deal less than the 76k miles than the truck actually had. It also explains why the motor was so clean.....

This is not a bad thing. :D Been looking into swapping heads to a smaller chamber to up the compression along with a cam and intake, and some fuel changes. Should put me right around the 400HP mark.
Re: 88GMCtruck's never ending 88 GMC build thread

Started some teardown tonight. Ran the casting number and date code, looks like it was cast February 14, 1996.

Some of the stuff that a Gen V / Gen VI block have. Aluminum valve covers, non-adjustable rockers, unique heads, revised cooling, revised oiling system, dedicated oil cooler ports, one piece rear main, and a 4-bolt main.

And the stuff that only Gen V blocks have. Mech fuel pump provision (gen V lost them), redesigned lifter valley with provisions for a roller cam, and a aluminum timing cover.

Been researching and I think I need to find a set of 96+ Vortec heads.
Re: 88GMCtruck's never ending 88 GMC build thread

No pictures, but I have some news.

I got a killer deal on a never ran takeout roller cam and lifter setup from a vortec motor. $115. I could not pass that up. All the hardware to make this a roller. Then found never ran GMPP Mercruiser cam for $35. Picked up ARP head bolts for $45 and a GMPP zz502 timing set for $48.

So the plan is now run the mercruiser roller cam, it looks like it will pair nicely with the powerband I want. The mercruiser motors made a good deal over 300HP with vortec heads. I found a few sets just haven't pulled the trigger on them yet. Sort of waiting on funds at the moment.
Re: 88GMCtruck's never ending 88 GMC build thread

Received the GMPP timing set and ARP head studs today. My dad is giving me a Edelbrock Performer RPM dual plane manifold, so that will save a few $$. Have a few other parts to get ordered up, gaskets, heads, TBI rebuild kit, and TBI adapter.

This weekend the truck is getting the motor and trans pulled. Trans needs a rebuild while we are at it.
Re: 88GMCtruck's never ending 88 GMC build thread

Welp, didn't get quite enough motivation to pull the motor and trans, I did however do a bunch of other stuff.

Dad gave me an Edelbrock Performer RPM manifold he had. It's a squarebore so I ordered an adapter for it. Overall cheaper than buying a manifold outright.

Yesterday I pulled the heads and dis-assembled the TBI, and today I spent the afternoon sandblasting lots of parts and pieces. After pulling the heads, then cleaning.

Mercruiser cam, installed with Gen VI thrust retainer, and installed ZZ502 timing set.

Manifold and TBI sandblasted

While I was cleaning, Dad decided to remove the lump from the emissions ports. Figured since I'm running the manifolds they should flow somewhat decently.

Re: 88GMCtruck's never ending 88 GMC build thread

Looks to be coming along good! I'm jealous that you will have a 454 in the truck. I'm in the same boat as you, the TBI 350 I have runs fine and has good compression and all, but not the power I need/want. I will need to research like you a way to change that. Keep up the good work and I can't wait to see how this build turns out!
Re: 88GMCtruck's never ending 88 GMC build thread

Another batch of parts arrived!

Factory take out Gen VI 454 Roller setup. I won't be running this cam, it's a stock L29 Vortec cam.

454 Roller lifter VS Flat Tappet lifter.

Roller lifters installed with dogbones

Retaining plate

Comparison of Gen V and Gen VI pushrod guides. The Gen VI ones are labeled "Hi Perf" which makes me considerably giddy.

I also sent off the engine specs to TBICHIPS to get the custom chip process started.
Re: 88GMCtruck's never ending 88 GMC build thread

Still waiting on the heads to show up next week, so i'm trying to get all the little details worked out now while i have time. One of the details that has been driving me crazy is the passenger side accessory bracket. The donor was a non-A/C truck so it had a dummy pulley. I'm going to retain A/C in my truck. I've been searching for weeks to try and find a bracket locally (or one online cheap) and haven't had much luck. In my searches I did find this

Adapters from Kwik Performance. They utilize the aluminum 2-piece brackets GM used on 90-94 smallblock and V6 motors. After being unable to find the 454 bracket, I went to the junkyard and snagged up these.

The right one is driver's side alternator and power steering pump bracket. The two left are different variations of the passenger side bracket. The middle is A/C only, left is A/C and Smog pump. Why on earth did I buy a smog pump bracket?

No, i'm not running a smog pump. It is the perfect location for a second alternator. After thinking about it and considering I have a spare, I figured why not? It will be isolated from the main electrical system. The idea is it will run a few accessories, primarily a 110V inverter, and be wired to charge the trailer while driving. The inverter will be able to power tools and such, as well as a 110V air compressor that I have.

Took a bit of grinding and cutting, but here is the result. I'm not 100% sold on it's position yet, as there is another alternator clocking out there that might look better?!