Q: I have a 1941 Ford sedan with a small block Chevy. I would like to replace the TH-350 transmission with a TH-700-R4. How much difference is there in the physical size of the transmissions? Will I need to change the transmission mount? Would the driveshaft need modification?

A: The TH-350 is 27¾ inches in total length and 20¾ inches long from the front of the transmission to the mounting pad. The TH-700-R4 is 30 inches in total length and 22¼ inches from the front to the mounting pad. To use the TH-700, you will have to move the transmission mount crossmember back 1¼ inches, and the driveshaft will have to be shortened 2¼ inches. The driveshaft yokes are the same on both transmissions.

This is another in a series of weekly Q&A Mailbag sessions with Summit Racing‘s tech department, in which there are hundreds more. Click here to see them all

Share this Article