Thanks Grigg,
I was trying the calculator but did not have all the pertinent data.
I did not know the transmission ratio at 4th gear. I do have a 1955 235 ci engine. I can get this rear end differential circa 1994, with disk brakes and low mileage for $350.00.
Another question would a v8 engine make a difference? (replacing the 235 ci )
Chris
