Whats the best way to change a 66 coupe from a 8in to a 9in? I have a donor rear, housing and all from a '65 289 car. I was wondering if it will just mount up into the existing points, and/or do I have to change the leafs or anything else in the suspension? I already have plans for converting the front to a 5 lug set up so thats taken care of.

 

pretty much a bolt in deal, cant remember about driveshaft length and U joints, its been a long time. Why not just get everything from the 65? Check the F.A.Q. for the I6 to V8 swap info as to what needs to be changed in that respect.

 

http://www.midnightdsigns.com/Mustang/Rear_Brakes2.htm

See if this helps any....

Are you sure you're swapping an 8" to a 9"..... or are you really swapping a 7.5" 4 lug rear to an 8" 5 lug rear? The reason I ask is you said the donor came out of a 65 289 car. 98% of those are 8" rears. For it to be a 9", it would have to have come out of a K code car.

If the donor rear end came out of a 65, then it has the spring perches welded in the correct locations, and should be a simple swap.

1) Are the brakes in good shape? (Now's the time to rebuild them)
2) You don't have to change out the springs and shackles, but if they are worn, now's the best time.

 

What he said.

 

Even if its an 8" he is putting in, its still an easy swap.. Most cant tell the differeence in the two anyway. Hence no mention, since someone could have put a 9" under the 65 at some point.

anyway, easy identification. Bottom bolt on the 3rd member, if you can get a deepwell socket on it, you have a 8", if you need a wrench to get it off, its a 9". If both rear ends have a cover on the back, you are wasting your time, unless one is from a Fox Mustang. In the case of a Fox, its not a simple bolt in, but it can be done.

 

From what I have been told about the 9in rear is that there are no bolts on the rear cover and the top or the housing is rounded opposed to the 8in being flatter on top, is that correct? I guess I will grap everything from underneath the 65, its really rusted up, so I guess I;ll clean it up and hope its still good. I'm thinking of buying a '66 i6 that needs some cleaning up and converting it into a FI 5.0, t5, I already have the engine and trans lying around so I decided to get something to put them in.

 

The only 65-6 that had nine inch rear ends where Hypos and Shelby's. The Nine is not that common in the early cars. Are you sure it is a nine?

 

Both 8's and 9's don't have bolts on the back, there is no rear cover as far as I konw. The best way of telling is the bolt on the 3rd member (front of the rear end where the drive shaft comes in). Some people will tell you that the back of all 9 inches had a hump in them where as 8s were flat. BE CAREFULL that is not always true. Some early 9's had flat looking backs, my dad has one. If you need more info check out this site. It is very helpful. In fact you should read it just to learn more.

http://www.kevinstang.com/Ninecase.htm

 

Thanks scott that answered my questions and then alot more. I guess I'll check the axle again tomorrow and see if it is or isnt.

 

Please let us know what you find out!