I've now got two 64's (love the heck out of them) one is a PG, the other is a 4 speed, one has a perfect body/paint the other not so much, its a long term project, but in the near future, I am going to run the 409, with the PG and 4:11 gears posi unit I bought, I may not like it for the whiplash effect, But since I have three different rear ends(3.08, 3:56 or :55, cannot remember) to play with, I'll just keep playing with it to find the right mix, but the goal is the 409 with the 4 speed at the end of the day, the rear ends, I'll just keep swapping my units in and out till I find the right fit for me. I am running 29.5 tires