5.2 in a 68 Barracuda

That's OK about the rear - I may just advertise it on CL and see if anyone wants it. This is rock crawler country around here!
I have an 8 3/4 rear down in the barn. It's supposed to be a 2.76 or 2.94. Don't know if that's right or not. Don't have any idea yet whether the width would be compatible.

The owner of the D100 doesn't know what's in it now.