I'm replacing my 318 with a 73 340 so was wondering if I could just swap out ring and pinion gear in my 7.25 rear or should I go with a 8.75 rear. 318 seems to wind out with rear that's in now so figured it prob wouldn't be good for a 340. If in need of a 8.75 anyone know of one for sale?

 

Personally I would not spend the $$ on a 7 1/4 diff
talk to Cass @ Doctor diff in MT he wil have a solution for you .

 

UNDER NO CASE USE A 7 1/4 rear end, for ANYTHING. its a good door stop.
this is a very good potters guide. http://www.crankshaftcoalition.com/w...er's_guide

 

Go with the 8 3/4 & a 3.23 gear or 3.55 for more performance