I saw a number of 2.47 diffs that had the large single mounting bolt, and some people say you can just swap rear covers with those. I didn't want to gamble. The 2.47's that I used with the trapezoidal mount on the back were from a 380 and a 420 SEL. Even though the housing is bigger, it will fit. The alignment is tough for the 4 upper bolts, and it will look for a few minutes like there's no way it fits, but it does. Good luck, you will be very pleased. Keep us informed as you go..