Rear end question
 

i was wanting to put a 9 inch in my stang but im not real smart about some stuff. I have the 8 inch in the back of my stang and was wondering what all you would need to convert it to 9 inch, would you need just the housing and spider gears from a 9 inch or would you need the axels and all ...i wasnt sure if the axles fromt he 8 would attatch to the 9

The whole thing
 

You can get it from Currie in Ca. in 8" or 9" in any ratio/w/ Traction-lock or anything else for a price.

Rev

Well, I put a 9" in my '66 stang almost a year ago, the only drawback so far is that because of my lowering springs and the poor angle/location of the exaust pipes over the axles, it bottoms out on the pipes (due to the heavier weight). It's deffinetly a lot stronger and it builds up your confidence knowing that you have a beefy rear to back up the motor.

All 9"rearend parts differ from 8". New axles, housing, etc must be purchased. I got most of mine on Ebay and through Currie Enterprises. It can be tricky finding the proper housings and axles and this takes some time if you plan on assembling it yourself. Make sure that your lug patterns will match from axle to wheel. The most difficult part for me was finding a U Joint that would bolt from a 9" yoke to the stock 8" drive shaft (because they have different journal sizes) . However, after many partstores and days of searching I did find one. But they're slowly becoming extinct. I'll probably have to update the driveshaft soon.

Good luck! -Matt

Yeah, U-joints with different size journals are difficult to find but not impossible. Most places don't stock them but they'll order them and in a day or two you're rolling.
I'd suggest going to a junk yard or a Pick-A-Part, and just buying a whole 9-inch rear. If you can find one from an 80's lincoln you'll even get the disc brakes! lol Measure the distance between the seats just to be sure it'll sit on your springs and then just bolt it in. As long as you're rolling you can beef it up in stages. Chances are the axles, unless they have surface rust on them are still usable. The all you need is posi, if you dont already have it and new bearings and gears.