Rear end
 

I have a 68 coupe with a 289. I was wondering if the older mustangs came with 8 inch or 9 inch rearends.

I know the 65 -66 had 8 inch. I would bet that yours has an 8 inch too. Hopefully someone else can confirm this.

Rwhite65, fastback, aod, 4.10, 306

Wow... There's something I never even thought of.. I kinda just assumed all the older one's had 9's in them...

Yeah!! I assumed the same thing, when I went to install my new 9 inch posi into what I thought was my 9 inch rear, boy did I figure out quick that my car had an 8.

rwhite65, fastback, 4.10, aod, 306

If you were fortunate enough to have a "K" code 289 Hi-Po, Ford was nice enough to give you a 9" rear end in your classic mustang.

They also put 9" rear ends in the big block mustangs, such as a 68 428 CJ. However, for 90%+ of us, we get the 8" stock.



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http://www.comports.com/2bav8

So if was to but a 351 Windsor in would I have to change the rearend to a 9 inch?

8" rears will work with a posi, if you build it moderate 300-400hp. but the 9"rears are tuff almost indestructable.

this is what caused me to switch to a 9in
http://www.inficad.com/~darkknight/Rearbk.jpg
hahah.. max gear ratio I've found for an 8in is 4.63..so, if you want steeper..outa luck
the 8in should be fine unless you run some HP and a 4spd..and yeah, the 68 came with the 8in..like 2bav8 said

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84 convt,'95 302, performer
3.55's, underdrives shorties
and a '68 stang that WAS nasty ;-)

easy way to tell,you need a wrench to remove one of the nuts on the front of the pumpkin on a 9".a socket will remove all of then on 8" and 8.8"
mike,
69 mach one,351C.

On an 8 inch, the pumpkin does not fill up the underneath of the car as much as a 9. As for an 8.8, it has a removeable rear cover.

9" rears have a bulge to accommodate the larger diameter ring gear. 8" rears look like a smooth dome on the hoghead.

I believe that the 351W's came from the factory with 9" rear ends. The 8" units were used on I6 and small (read lower power)V8's. Hence, my kids 69 SportsRoof with a 351W has a 9" unit and my 69 convertible with a 302 has an 8" rear end. That also explains the 9" in the early HiPo V8's.

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Most of the information here is correct. I would guess that 90% of all V8 Mustangs originally came w/ the 8" rear. Only the Hipo's or cars with a 351 or larger engine ever got 9" rear ends. The I6 cars actually came with a 7.5 inch rear that used 4 lug wheels. I have to say that the best improvement that can be made on one of these cars, regardless of ring gear size, is to change that rear gear to something more performance oriented. On my current car, I only changed from a 3.00:1 gear to a 3.40:1 gear, a small change, and found response to be MUCH better. I can only imagine the difference to a 2.80 geared car going to 3.55 or 3.89 gears would feel. http://www.mustangworks.com/msgboard/smile.gif