If you're not going drag racing just an 8" should do fine. If you could locate one out of a Maverick, the length should be very close for your coupe!!!!!! With the OD, you could easily get into the 3.70 range and still have decent RPM on the highway.... 3.25's or 3.50's with the od should really let the car loaf down the highway at normal cruise speeds. With $3.00 guess prices here next month, might be a really good way to go...