I'm taking a 283 and a 2 speed powerglide out of a 1967 C10 and replacing it with a 350 and possibly a 3 speed auto. I was wondering if i need to replace the differential and drive shaft for any reason, and what would be the gear ratio
Measure the length of the tranny's. If they are the same, your good. If not all you have to do is take a good measurement from your yoke (on the rear end) to the tail shaft on the turbo 350 transmission you mentioned to a driveshaft shop and they will do the rest. Normally about $40 to have one shortened/balanced. No need to replace the differental unless you are wanting to do a gear swap. By the way the 2 spd powerglide is a sought after tranny for dragracers. They go for around $300 where I live and that is just a core that needs a rebuild.