What the heck is up with 8-3/4" rearends?

I paid a bundle for my 8.75 with sure grip ans 3.23 gears, fresh quality rebuild, drum to drum. And I drove 350 miles to get it. 1300.00 Dollars. But to me well worth the bread.

Do you need a 742 pumpkin w/a 30 spline spool and stock length a-body axles out of my 9-second Dart by chance?