I have an 87 with a700r4 that's pretty toasted. After discussing it with alot of people. I'm gong th350. I've read the forums but haven't gotten all the answers I need. If someone has a link to a swap please send it my way.

I know I need a 9in tail th350 so I can use the same driveshaft. I now I need to weld up a bracket for the torque arm and a plate to move the Trans mount.

What about the output shaft? Direct fit?
Trans cooler lines direct fit?
Anything else I'm missing?

 

That's pretty much it. I did the swap 11 years ago. I just fabricated an extension plate from 1/4 steel that goes between the crossmember and trans mount. I made it long enough to install an adjustable "L" angle with multiple holes to bolt the torque arm to. That way I can adjust the pinion angle. Very simple and all bolt on.

 

Get another 700r4 dont downgrade the car with a TH350

 

Yeah I just did the same for mine and its all working fine now.

 

Keep that 4th gear! Not much money to have one built. Don't just get a rebuild on that 700 either. Get it done right. Find the cause of failure, and throw a couple upgrades in it too, not just a shift kit.

 

TH350 or TH400 are much better transmissions than a POS 700r4. Cheaper to build and far more capable of holding decent power. The way most of these cars are built now, who cares about overdrive in a toy that gets driven a couple times a week. My buddies 87 Trans Am TPI swap was noticeably quicker with a 2,800 stalled TH400 and 2.73 posi rear than it was with a 700r4 and 3.08 open gear. Cruises 70 mph @ 2,500 rpm which is about perfect for the LT4 Hotcam to run smoothly. 700r4 + highway gear have no place in a hotrod.

I put a TH400 in my old 83 G20 van after smoking 3 POS 700r4s and 2 newer 4L60Es. I could have bought 3 gearvendor overdrive units for the money I spent to "build" those junk transmissions.

I 4L85E swapped my 97 Express after the stock 4L60e grenaded at 38K and the built 4L65E exploded 40K later. At 78K the near stock 5.7L Vortec was on its 3rd trans. Junkyard trans had 110K when swapped in and is still going strong behind the ~500 hp 383 pulling a travel trailer. I wish I had the money I spent on the 65E to have a gear vendors behind the junkyard 85E. I put a class 4 hitch on the van after the 85E swap, confident I could finally actually tow something. I have towed with it since 2013 and the 85E does not complain.

i will never spend a penny on a 700r4 derived transmission ever again. 700r4, 4L60E, 4L65E or 4L70E ALL are garbage to me.

 

Question for the OP
How much power your engine making?
Using it for a lot of hwy miles? or the strip?
What tires?
What's your budget?

 

See my new post about a DIY crossmember mod for this swap.