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Th-350 on my 6.2

k5blazin

k5blazin

1/2 ton status
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Dec 19, 2004
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Elizabethtown, PA
my 700r4 is showing signs of blowing out on me so i was thinking an upgrade to a 350. will it bolt up to my 6.2? how will i rig the kickdown so it will work with the 350? i already bought a kit from TCI for the 350 to bolt up to my 208 t-case so thats not an issue. what other things do i need to do to make this happen?
 
First off a th350 is not really an upgrade from a th700r4, it's almost a step back IMHO. If you are having problems with your 700 I would not mess with a 350 but instead go with a th400. The 400's in military trucks are setup for a diesel and a th350 really isn't any stronger than a th700r4.

The transmission will bolt up just fine. The problem I see is getting a converter and governor to work. There was never a th350 behind the diesel (IIRC) so getting the right parts from GM is probably out. Maybe an aftermarket company like TCI carries custom low stall stuff that would work but I don't know...
 
ok thanx for the input. i was also thinking about building a 700r4 because i work in a tranny shop and i have a good core laying around. i could build one really cheap and it would have some stoudt to it. would that hold up well to my 6.2??
 
You can build them to a point, but it all really depends on how you use the truck. If you have a heavy right foot and big tires with high gears...

What size tires and what gear ratio are you running? That is one of the most often overlooked causes of failures with the 700R4 (35" tires and 3.08 gears for example).
 
Well i have stock lift and 31in. tires for now cause i just got the truck. i will be adding 35 or 36 inchers with a 6 in lift with 4.10 gears in the near future. i think if i keep the fluid cool the tranny will do alright with the lift/tires/gears.
 
If you're seriously thinking about 35's or 36's and a 700R4, go with a 4.56 gear. The OD will make up for the deeper axle gears, but the bigger payoff will be the reduced strain (therefore HEAT) on the tranny when getting the beast rolling. Run the biggest cooler you can, and change the fluid religiously (20K mi is the consensus I've reached).
 
k5blazin said:
ok thanx for the input. i was also thinking about building a 700r4 because i work in a tranny shop and i have a good core laying around. i could build one really cheap and it would have some stoudt to it. would that hold up well to my 6.2??
Click to expand...
I would jump all over that!!! I'm sure a built th700 would stand up to a stock 6.2 easily and probably a turbo'd one too. I'm making about 300 ft lbs of torque to the ground with my 406 gasser and a built th700 which is a little more or a little less than what a 6.2(depends on who you ask ;) ) puts to the ground and I have beat the crap out of my built th700.

SInce you work at a tranny shop you know all about keeping fluid clean, cool, and the coolers they require. But gears are important. At least 4.10's with preferably 4.56's with 35's or 36's.
 
yea thats what i was planning on doing. i have my eyes set on the B&M cooler with the aux. fan bolted to it. and like i said i work in a tranny shop so fluid changes will be no problem. im going to do a fluid change this weekend to see if the tranny will staighten out because it hasnt been driven in 2 years. it might just be low in fluid too so ill check in the morning.
 
What year is it? Actually (I may be completely wrong so someone correct me if I am) I don't hear of as many 700R4 failures behind the diesel as I do the 350 gas engines.
 
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