Th400 Or 700r4

[Vince M]

The selection of the 700r4 is great if you have the right gear ratio in the rear end. It sounds like you have a 3.73:1 ratio which the 700r4 will work great with. You can even go to a 4.10:1 and it will work great. If you have a 3.08:1 the fourth gear will drop the enginge revs too low at freeway speeds.
With a lockup you can keep the transmission oil heat down and even gain a few hundred rpms of more overdrive.
With the right mounting the 700r4 will bolt right into the same location as the TH400. You want a tail section that has the mount on it. This gives you pan clearance with the crossmember and it will use the same tranny mount and crossmember as a Th400.
I put two 700r4's in now and with the right stuff it works great.
With a 3.73:1, a 700r4 and 30" diameter rear tires I was doing 1800 rpm at 70 mph in lockup. You won't need to turn the radio up anymore to drown out the motor.