It's a 7 1/4 inch 10 bolt wonder. Cuz it's a wonder mine still works after 47 years and 240,000 miles.

To upgrade to an 8 inch just find a good working one for the year car you have and bolt it in.  Everything bolts to the same places I believe. Check on the drive shaft. You also need to worry about your wheels

Welcome to the forum!

Last edited by Muzz 66 (10/21/2013 1:17 AM)

I ran one behind my 302 for several years without beating on it too much but I replaced it with a 9" a couple of years ago when I upgraded everything to 5 lug.  I think most people would recommend you replace it.
Good luck,

Mustang Guy wrote:

Will the 7 1/4 hold up to a 302 or should I up grade.

 You need to upgrade. 

I have a long-winded story about stopping to help a kid with a 65 Mustang that was stopped dead in the middle of a busy 3-lane interstate highway. 

He was laying on the ground in front of the car trying to figure out why the car would not move.  I pulled to the shoulder nearby and convinced him it was not a good idea to lay under the car with it in that position.  He came over to the shoulder.  I told him that next time a clearing of cars came up, he would jump in the driver seat and I would push him to the shoulder.  Clearing came, we tried it and the car would not budge.  The rear end was locked up solid.  A 4-lug rear end with a V8 in the front. 

We stood there and watched from the side of the road as all the un-alert drivers spotted the dead car in the middle of the road ( of course it had no flashers) and swerved at the last minute to avoid rear-ending it.  A suburban nearly hit him and then swerved and nearly hit the center guard rail and then the right side of the road and finally got it straightened out.  Then some lady in a Windstar minivan, apparently intent upon watching the suburban, swerved at the last minute and caught the left rear of the Mustang with the right side sliding door area of the van.  It ripped the door off the van and then spun it around so it was facing the opposite direction, expelling the entire contents of the inside of the van all over the interstate highway, blocking both directions of traffic.  It is darned lucky she did not have an unbelted kid asleep on the rear seat.  She and her son were belted in front and did not get hurt.  The Mustang was totalled immediately. (unless you are Ramses).

From that day on, I have been a big proponent of doing things right when you are messing with something that can cause a wreck or be considered a safety item.  That 4 lug rear end locked up and diasbled the car in the center lane and there wasn't a darned thing anyone could do but sit there and watch the car get creamed.  It is lucky no one was killed in the process, including the inexperienced Mustang driver laying on the pavement in front of the car.

Yes, you need to upgrade the rear end.  Do not take chances with something that can fail catastophically.

An 8" from a Granada is a straight bolt in.  The 8.8" rear is a good choice but takes considerable more work.  You do get more out of the deal though as they are stronger than an 8", you can get discs cheap and a traction lock at the same time, along with a decent ratio from an Explorer.   A 9" is a good bolt-in, but getting rare, and unneccessary unless you are making alot of power.

Thanks for all the help in this matter lookslike a up grade is coming for the old girl like I said thanks.

if you want to stay 4 lug but still get a 8" you can get a 71-73 6 cyl maverick rear end its 4 lug and 8" and will bolt right in to the 65-66 mustang it is about 3/4 of a inch shorter then the 65-66 8" axle but thats not bad i have one in my stang and it bolted right in i did not even have to change drive shafts as i have a c4 trans it even uses the same drum brake componites as the 6 cyl as well.