Automatic transmission options - The 1947 - Present Chevrolet & GMC Truck Message Board Network

72k20410 · 07-15-2003, 09:10 PM

I am in the process of restoring a 72 k20 and have a few questions. It has had its enging and transmission rebuilt at some time but other than that it is completely stock. It has a 350 and AT with a 205 t/c. First question is what kind of trans came stock on a k20, was it a TH350 or TH400. The build sheet just says hydromatic trans with some kind of code. Does anyone have a list to decode the option? Second question, can I fit 35 inch BFGs on 8.25 rims with a 4 inch lift or will I have to cut the wheel wells?
Thanks

Here are some pics of the latest projects.

http://community.webshots.com/album/49140507zDjBsp

Rod · 07-15-2003, 11:24 PM

72 K20 and all trucks 4x4 in this era that are automatics came with turbo 350's.

1969 GMC · 07-16-2003, 12:32 AM

about your second question, i too would like to put a 4" lift and 35's on my truck. the general consensus seems to be that it is fine for driving and flat surface wheeling, but if you get into the twisty stuff, you will hit something with the tires. i believe they will clear fine. my truck has 32" tall tires now, on a stock suspension (saggy front springs). i figure with good front springs and a 4" lift, it will be just fine. i want to get the skinniest tires possible, to keep a retro look about it. i want to know if BFG makes a 35x10x16 or so tire, they probably dont, but oh well.

also, 4" seems to be the cutoff on steering mods. if you want more than 4", it seems you have to go with crossover steering.

good luck on the mods!

07-15-2003, 09:10 PM	#1
72k20410 Registered User Join Date: Jul 2003 Posts: 1	Automatic transmission options I am in the process of restoring a 72 k20 and have a few questions. It has had its enging and transmission rebuilt at some time but other than that it is completely stock. It has a 350 and AT with a 205 t/c. First question is what kind of trans came stock on a k20, was it a TH350 or TH400. The build sheet just says hydromatic trans with some kind of code. Does anyone have a list to decode the option? Second question, can I fit 35 inch BFGs on 8.25 rims with a 4 inch lift or will I have to cut the wheel wells? Thanks Here are some pics of the latest projects. http://community.webshots.com/album/49140507zDjBsp

07-15-2003, 11:24 PM	#2
Rod Join Date: Dec 1999 Location: Eastern - Manitoba Canada, Winnipeg Posts: 4,369	72 K20 and all trucks 4x4 in this era that are automatics came with turbo 350's. __________________ Senior active founding member. 70 3/4 ton GMC Suburban 4x4 250/4 spd. 71 1/2 ton Suburban Chevy 4x4, 350/350 72 Chev 1 ton tow truck 402BB w/Holmes 440 wrecker on propane 2005 FLSTSCI Harley Springer 85 FXSB Harley Lowrider 72 Triumph 650 Bonneville 5spd "Poor people don't have hobbies" Quote from wife.

07-16-2003, 12:32 AM	#3
1969 GMC Registered User Join Date: Feb 2003 Location: The Rubber City Posts: 5,498	about your second question, i too would like to put a 4" lift and 35's on my truck. the general consensus seems to be that it is fine for driving and flat surface wheeling, but if you get into the twisty stuff, you will hit something with the tires. i believe they will clear fine. my truck has 32" tall tires now, on a stock suspension (saggy front springs). i figure with good front springs and a 4" lift, it will be just fine. i want to get the skinniest tires possible, to keep a retro look about it. i want to know if BFG makes a 35x10x16 or so tire, they probably dont, but oh well. also, 4" seems to be the cutoff on steering mods. if you want more than 4", it seems you have to go with crossover steering. good luck on the mods! __________________ 1969 GMC K2500 1996 Honda Accord 2007 Kawasaki KLR 650



Register or Log In To remove these advertisements.

Register or Log In To remove these advertisements.