Transmission Pans

[Heavytruck]

I have an Allison (2005-2WD) tranny. I go down to the parts store for a screw on and internal filter. They ask "deep or shallow pan?". Of course they can't give me a dimension. So, from the flange to the pan bottom, what is deep, and what is shallow?

[Mark13]

If it's the stock pan it's probably the shallow pan. I have an Allison deep pan on mine and it's probably 1.5-2" taller then the stock one.

[Nasty-Z]

AFAIK ,

All of the Allisons that were in the light duty trucks (2500HD & 3500) were "Shallow" pans , about 1-1/2" tall, Heavy trucks ( buses , 4500 , etc) got the "deep" pans which measured 3-1/2" or so deep .

If you swap to the "deep" pan the gasket is the same , the internal filter is the only difference .

NAPA part # 18668 for the shallow pan and 18669 for the deep pan , this is a filter and gasket kit.

If you want to re use the OEM gasket (which is perfectly fine) , P/N 18662 for the shallow pan and 18663 for the deep pan filter only .

FWIW , Allison reccomends internal filter replacment at overhaul , replace the external spin on at service interval time , not that i'm saying not to replace the internal but .....

The external spin on filter is NAPA P/N 7701

HTH

TOM

[Heavytruck]

Thanks. I would say shallow. I know it's overkill but I bought the truck used. I am going to drain the pan. Change the external filter, add the required amount of Mobil 1 ATF. Then after a week or two, drop the pan, replace the internal, and external filters, and add the required amount of Mobil 1 ATF again.

[mwall]

If the Mobil 1 ATF that you plan to use is a full synthetic ATF be warned that if your Allison trans wasn't built for synthetic ATF (pre 2006), you could cause the external seals to leak. A friend of mine put fully synthetic ATF in his 2002 HD w/ Duramax/Allison and the front pump seal started leaking badly after a few months. He took trans out and resealed the front pump but the leak returned a few months later. He then checked with an Allison trans shop and found out that the synthetic ATF tends to cause the seals to break down and leak. GM and Allison have tech bulletin on this and there is tons of info about this on the internet....

[Heavytruck]

Thanks everyone. I may have changed my mind on fluid use again. There seems to be a lot of confusion. I have read that Dexron III is the factory fill for light duty trucks. Then there are fluids that meet TES-295 spec, and fluids that meet TES-389. One thing I've also read is that 2005 and earlier are not Dextron VI compatible. I also found out that Mobil 1 synthetic ATF and Mobil Delvac Synthetic ATF are NOT the same. Mobil Delvac IS TS-295 spec, but Mobil 1 ISN'T. As far as Syn vs Petrol based, the are cross compatible. I'm not sure what made your friend's seals leak. I've changed over rear ends, transmissions and engines from petrol based oil to synthetic without issue.

[Koots]

I was told that Transynd is the best option out there, some synthetic ATFs may be better, I don't know.

[Midwestrider]

Nice