So Its a 5 lug, obviously I will need 2 5 lug rims. what all else will be involved in putting the 9" in? Its from a old ass ford truck, maybe a late 70's early 80's f150 custom. Will it work, and If so, what gears do you think it comes with?
It will almost certainly be too wide, not have the right suspension mounts, and require you to figure out what type fo driveshaft setup you need to work with it. And if it's in a truck it could have anything from a low 3 to a low 4 gearset I suppose.
But the real question is why? An 8.8 is plenty strong to hold up to serious power, and most certainly cost less than doing all that work.
cutting the axle tubes down about 4 inches on each side, shorter axles, fabricated control arm mounts, fabricated shock mounts. You could build 2 bullet proof 8.8's before you got up to the 9inch in price.
I would say no on the truck 9. Not only would it be a pain to mod and cost a lot of money, it would also drain lots of power. Those things can sap up to 60 horses because they have such large running equipment. Your 8.8 can easily handle 600+ horses.
I sold my 8.8 and the profit's from it bought me a Moser 9" Bolt in Housing with Moser Axles and bearing's. It was cheaper for me to build up a 9" as I had tone's of part's laying around for them. (Nodular Housing, Locker's, Gears etc.) Not only that I find the 9" way easier to work on and I needed a strong rear end to handle the 408.
As for a mild Mustang like Saltymaz I would stick with an 8.8... it's all you really need. It would cost you alot more money to do the 9" swap and not only that but the 9" is heavier. Modifiying a truck 9" to fit a Mustang would be VERY time consuming as well and would require alot of skill to have the Mustang 4 link suspension geometry lined up perfect.
Believe it or not most of the 80's F-150's I have owned or worked on had 3.08's in there. The 5 bolt from a 150 is a biger pattern than a 5 bolt car. The pattern from a F100 is the same as most ford cars. I think it is 5 on 4.5 (for cars).
Just an FYI a 9 inch ford takes a tad more HP to turn than an 8.8.