Long post ahead. I got a PM and see many threads addressing questions about how to go about static drops and how they work in real life, so I thought I would make a post putting my .02 cents in, having driven a 96 chevy extended cab slammed 5/8 every day for 8 months now, day in and day out.
I'm going to give you all some good advice, because I have learned a lot working on my truck, doing all the work myself, and having to rely on it for sole transportation (which can be tricky at times like now, when its down most of the time for a full custom paint job
) . Anyway, as far as the suspension goes, I was/am in the same boat as you. I started with a 3/4 drop, and while it was cool and very streetable, I didn't like the rake too much. I wanted bags, couldn't afford it at the time. The reason I went with the 5/8 was because I already had the 3" coils and 2" hangers. That was mistake #1. Hangers. They are a total pain. You have to pull the bed to put them on and the rivets on the driver's side are blocked by the gas tank. So, I went my merry way to the local hot rod shop and picked up a 6" flip kit and 2" lower control arms. Mistake #2. LCAs + coils = alignment issues. I'm going to swap them out for spindles, and I will be able to align it all back to spec, and they wont rub the inner lip of my $600 apiece wheels like they do now
Now, a 4/6 is a very streetable drop. The only real thing you have to cut is the frame for the bolt in notch. Sure, a 4/6 is cool.. but you want to go that extra mile right? I did. So, when you take the plunge and go 5/8 ( you know you want to
) you'll want to use 3" coils and 2" spindles in the front, and a flipkit and shackles in the back. You could think that you'll be okay on the bolt in notch like I did, but you'll hate it instantly. There's no travel. So, knowing that I will want bags later, i went ahead and cut the bed out and welded in a monster notch from Suicidedoors.com . But, if you dont want the big hole and dont care about laying out all the way, get the same notch i did ( the 8" one ) and just trim it down to fit under the bed floor. I have plenty of travel in my notch, I can lay frame on 22s easy. Now, for the front, anything lower than 4" and you have to cut a notch in the frame for your tie rod ends. If those break youre screwed. You'll also notice your swaybar doesnt fit. Dont chunk it - I ran without it for a while and yes, it does make a big difference in these big trucks. What you'll need is some shorter endlinks. However, if you use DJM lca's, you'll notice that their brilliant engineering department designed them so that the swaybar is at some goofy angle and you end up busting out your bushings. Solution = redrill and tap the swaybar mounts on the frame. Also, dont forget your carrier bearing shim. Nothing is worse than taking off from a stop and getting that extra vibration jiggling your hot, expensive Starbucks all over your dash. If you go 5" in the front, and even with a wheel and tire combo that equals 27" in overall diameter like my 20s with 255/35ZR20 tires, you'll need to cut out or better yet modify your inner fenders in the front, cause rubbing them and bumping them sucks. And for peace of mind, even though my billet Intro wheels tuck perfectly, I rolled all 4 of my fender lips - no worries. And if your roads even slightly suck like they do here, you'll want a slightly larger profile tire, like a 45 or 50 series, something in there. Good luck, and remember - No fat chicks, the truck will scrape!
Cody