I'm in the process of swapping a 700r4 for a th400,but as of yet do not have the th400. I know the mount on the th400 is some 4 1/2" further back from the existing 700r4 mount pad,but what about the difference in height?Can anyone measure a th400 tailshaft and post the measurement from the output shaft centerline to the mount pad on the tailshaft housing. I need to fab a plate to complete the swap and would like to make it up ahead of time if possible.

The 700r4 measured 1 3/4" from the mount pad to the center of the output shaft.

2 1/8 from mounting pad to center outputshaft on short 4in trans

what are you putting it in?

Full manual reverse valve th400 with a 2400 stall.

Full manual reverse valve th400 with a 2400 stall.

is your cross member weld or bolted in? this should be a direct fit. with the correct crossmember.

you have to cut off the front tabs off the case to fit it in a vette

The car originally had a th350c,which when the 406 was put in promply blew. I decided to "upgrade" to the 700r4 which was not stock in Vettes till 1982.At the same time I opted for a 3" dual exhaust.Fairly costly project that lasted one week before the 700r4 crunched on a 6500 rpm 2/3 shift.I had a local shop rebuild it,and managed to get one more year.This time the converter clutches went,plugging the valvebody and preventing any shifting.I decided to scrap the 700r4,but due to the expensive exhaust work,and custom crossmember(And PO'd wife)I am trying to salvage as much of what I have,that I can.Besides the driveshaft and yoke,swapping in a th400 should be no sweat. The crossmember is custom,and was designed for the 700r4.The location of the member is almost exactly where the th400 mount bolts should go.My plan is to bolt a 1/4" plate to the transmission,effectively extending the transmission mount forward an inch or so,and installing the rubber tranny mount to the plate,and crossmember. I have a concern the resulting height may be an issue,but maybe not. I'm thinking the tailshaft will end up 5/8" higher than the 700r4 was.

I rigged up a couple cheapo laser pointers that I will use to try to zero in the driveline angles.Plan is to bolt one to the pinion flange pointing forward,and the other to the tranny yoke facing to the rear. Then measure the distance between both laser beams at both ends,raising or lowering the tranny to get the beams parallel.Maybe not nessesary,but much closer than the "eyeball method".(I know...I've got too much time on my hands.)