my67_fastback

what are the different sizes of rearends that were in the classic mustangs? and what is different/better/worse about them? when did they (if they did) switch from one to the other? etc.

Colorado_Mustang

8" and 9" are the good ones. There's a 7.x" that is passable for the stock sixers.

There were several different versions of carriers based on the year for the 8" and the 9". Basically, the 8" will handle upwards of 500hp from a short deck Windsor. The 9" should be used with any large cube engine or a really high strung small block (generally the non-streetable types).

Shifty101Easy

500hp? really? i thought it was more like 350-400hp.

Hornblower

Not sure I would run an 8" rear with 500 HP at the wheels. You also have the choices of open rear ends where only one tire is pulling, or others where both wheels pull, and others where only one wheel pulls until that one wheel gets stuck or off the ground, then the other one kicks in. Old Mustangs basically had a choice of 2 rear ends depending on which Mustang you purchased. The 170 I6 had a 7.25", the 200 I6 had the 7.5" and the rest had the 8" except for the Hipo which had the 9".

Scott H.

www.ultrastang.com has a nice write-up on the 9". Very good information. A google and wiki search will turn up all kinds of information on the 8". The other option (my personal favorite) is an 8.8", and there is a plethora of information (right and wrong) on this unit.
Using HP as a limiting factor on a rear end, is a big mistake. There is way more involved than just HP numbers.

Good luck,

Colorado_Mustang

From a short deck Windsor, yes. From a big-block, no. A big block making 350hp will break an 8 inch...while a 302 making 350hp won't. The torque is the difference, which is why I stated the short-deck Windsor.

A manual tranny with a bad driver is also harder on the rear...same can be said for an auto with an over agressive shift kit.

The HP numbers are just ball parks, like saying a stock 302 block can take 450hp...depends on how that power is made.