I have this transmission sitting in my shed. TH400 short tailshaft.

If I was to swap it in, and not use a gear vendors overdrive unit, what rpm's would I be turning at say 60, 65, and 70 mph? I have 3.23's....

I am only considering doing this if it can be done relatively cheap. Hence why I am asking about running it without the overdrive unit. I can get a driveshaft custom length from the same guy that did my dad's 1957 Chevy, so thats not a problem. The only thing I am not sure of is how the shifter would work, and if I would need a different one and if it would fit in the stock console. Also not sure what I would do about the speedometer to get that to work. Any ideas?

Thanks guys

 

if the vehicle is many for weekend warrior or drag strip or mainly city driving, go with the 400......But, if it goes on the highway alot, stick with the 700r4... My 700r4 is build to handle 450-500 HP...JMO

 

700's 3rd gead or drive is the same as 400's high gear
ratio of 1:1 or direct drive

FYI 4th gear on m6 is also direct drive

 

OK, forget that then

I daily drive the car, to campus on the freeway. So I'd be better to get the 700R4 rebuilt if I need it

 

Assuming stock diameter tires (25.65") w/ the 3.23's, and NOT taking into accout converter slip, since the TH-400 won't be having a lock-up converter, so the RPM's will be slightly higher than calculated:

60MPH = 2539 RPM
65MPH = 2750 RPM
70MPH = 2962 RPM

 

What are the differences in 4L60's and 700R's anyhow???

 

The name pretty much, they have been doing that 4L60 stuff since the late third gen cars 91-92.