I have a 72 Demon that was originally a 318 3 speed, the rearend is 8 3/4 with 3.23 gears in it, I am putting a mildly built 340 in it with a 4 gear based on expiences out there how does everyone feel about putting 3.55 gears in it?
My advice is find a low 1rst gear four speed (3.09) if you can,they made some in the early 70s with std. output shafts (thats what I have-its a 1974) or you can covert an early trunion style over.When you look at the start ratio (1rst gear x rear ratio) my 3.23s are like 3.91s at take off but the freeway is smooth at 70+ since I have 275/60/15s (28in) tires.