7 1/4 to 8 1/4 upgrade with 2.45:1 gears

I just put a 8 1/4 in place of the origional 7 1/4 in my 64 Dart GT I put in a 1979 8 1/4 out of a volarie service vehicle (cop car, taxi) and it to is a 2.45 posi unit behind a 226 slant 6 with a 904 14" tires, bigger bolt pattern, I did get shafted by the machine shop who shortened my drive shaft what I called he told 50, and when I dropped it off he said thats the old style it will be a little more, yeah 110 bucks more, live and learn next time I will ask how much more. :glasses7: