Length of TH400 Trans?

[Sean]

This is in the newb section b/c I don't know shit about autos and I'm pretty sure (please correct me if I'm wrong) the tail housing is irrelevant for a 4x4 application since the adapter to the tcase replaces that tail housing.

That said, what's the actual length of the TH400 for a 4x4 application? From the image below, it looks like 25" to where the adapter for my tcases would bolt up. However, this Summit link says it's substantially longer: GM 3 Speed Transmission Dimensions something like 26 15/16" at best....

Everyone who's looked for different GM transmissions for a project has probably seen this image since it's all over the web. I'm normally a manual transmission guy so this is my first foray into a set of builds with autos going behind LSX 5.3 engines. I planned to use the TH350 b/c of the shorter length and wanting at least 3 speeds to go with my 3 speed tcases and portal axles. However, I'm a little concerned about ultimate strength of the transmissions and am looking at the TH400 now instead since price wise, the TH400 seems less expensive for what I want (reverse shift pattern, full manual valve body) while being stronger, but coming at a cost of weight and length.

So, which number is correct? 25" for the TH400 or 26 15/16" (to bolt to a tcase)?

 

[Corey Young]

The bare Chevy th400 case is 24.5" and the thinnest factory tcase adapter is 1.25"

 

[Sean]

The bare Chevy th400 case is 24.5" and the thinnest factory tcase adapter is 1.25"

I'd be running a Hero 3 speed behind it...with its own adapter to the TH400....so I wouldn't need the thinnest factory tcase adapter in addition, correct?

 

[Corey Young]

I would guess that the 400 to hero adapter is similar.

 

[Sean]

I would guess that the 400 to hero adapter is similar.

Appreciate the input.

 

[Corey Young]

If you do go with a th400 find one 1980-1991 4x4 or motorhome model. The same year 6 bolt converters are better then 3 bolt models. Also some manual valve bodies have a really hard downshift.

 

[Sean]

If you do go with a th400 find one 1980-1991 4x4 or motorhome model. The same year 6 bolt converters are better then 3 bolt models. Also some manual valve bodies have a really hard downshift.

I am planning to just buy a TCI (most likely), ATI or Hughes Performance built from their factory.....might get it through someone like Summit or maybe direct. I'm hoping by going full manual valve body that I get instant shifts (apparently the TCI reverse pattern full manual valve bodies are known for this), and I'd rather they be very firm than seamless anyway.