You can take the sure grip posi off a dana 60 35 spline. Remove the side gears and put them in a 8 3/4. May after to machine the od of the side gear a little not sure. Or have the side gears broached to 35 spline.
Yes there all interchangeable. I have installed rb internals in a sb case . No issues your. drums cracking is pretty common because there cast a good upgrade is to go to a steel drum.steel drums are a must when useing a trans brake. if you're using a used drum you should have it magnaflux for...