What casting rears are we talking? Limited slip is Sure Grip. Pictures? IMHO not worth swapping. There is a conversion U-Joint that will take care of the mismatch.
I mis-spoke. Mines a slip diff. The sure grip has bee gone thru with backlash setting friction discs, and seals. I think it's a 741 based on the casting #. I been out of the loop for 35 yrs. Forgot the little that I did know. Appreciate the help guys. I'll attach pics.