If I want to be able to shift without damaging the tranny (manual valvebody?) have reverse, no transbrake, and I want it new where do I go? I dont want a remanufactured one, I just want a transmission that wont fold under pressure, I hear this is THE tranny for torque monsters.
-Nick

 

The last TH400 to roll off the assembly line was in 1990. After that they became 4L80E (Overdrive, 4 speed with computer controlled valve body).

The weak link in 1970-1990 TH400's is the same as a TH350. The intermidiate sprag. You can upgrade to an aftermarket 34 element one however you need either an aftermarket direct clutch drum for it to fit on or find the direct clutch drum from a 65-69 TH400.

Internally the TH400 is much better designed to take more abuse than a TH350. That's why they're usually used in high performance use.

A TH400 is bigger and heavier than a TH350 and it takes about 15 HP more to turn it.

Depending what you intend to do with it, find a short tailshaft model from the mid to late 80's in the junkyard. Low milage is best. Either take it apart and rebuild it (not always necessary) and put a simple shift kit into it. If you want a manual shift valve body, they sell them without a transbrake. I'm not sure if they're offered in forward shift pattern or only reverse shift patteren. The manual valve body gives no automatic shifting. When you put it in drive you'll start off in third gear. At least with a shift kit you can manually shift through the gears but "D" is still an automatic shift.

You'll need a conversion kit to put the TH400 into a third gen. Finding a TH400 in a van or pickup truck will usually have a bolt on yoke. You'll need to get a TH400 slip yoke since the output shaft is larger than the TH350/700R4. You'll also need to get a new driveshaft made since the tranny is longer.

There are many places that will sell you a "new" reconditioned tranny if you want to take the short route. From what it sounds like you want is a typical street replacement tranny. Once they're rebuilt properly (seals etc), they're as good as new.

 

Yah I was gonna buy one rebuilt I geuss. thanx for all the info, im going to go with all the conversion equipment from spohn including the bolt in 9"
Im thinkin about a crate 502 in front of it all...
-Nick