I've got an automatic rx7 with a bad diff. I've got a 4.10 diff and well as a driveshaft from a manual car. I was wondering if it would just be a straight swap if I used the manual trans driveshaft and 4.10 diff. Otherwise I believe I would have to swap out Flange on the driveshaft?

 

The flange on the differential is different although it can be made to work. The drive shaft will not work as it is a different length and slip yoke is different. I have an automatic drive shaft out of my '93 for sale if you're interested.
Dave

 

I have put an automatic diff into a manual car. The flanges are different but I have a lathe and machine shop and was able to modify it to bolt up. This was 5+ years ago so I can't remember offhand what I did, but it is possible.