The '67 I just bought came with a spare 9 inch rear. Axles are 27 spline. Depending on which way I go with her, is there any real advantage with doing a rear swap? I haven’t found a tag yet (everything including the chunk is apart), but is there any possibility it could be a limited slip or did they just come 31 spline? Or do I even have a clue what I’m talking about? LOL!! At this point I’m thinking just clean it all up and recoup some $$, but if it should happen to be limited slip, the idea of having it is appealing.
Thanks
Chuck
In 1967 all rear axles were 28 spline whether 8" differential or 9". Post some pictures of the differential, it is easy to tell if it is a Traction Lock or not.
Thanks Royce. Guess I miss counted. I’m not sure, but I think he said it came from a Mustang, but I have no clue what year. I won’t be able to get a picture of it until when I am off next Monday/Tuesday, but will do so and let you know I have posted it. Thanks for the proper name of it also. I knew it wasn’t ‘posi’ but couldn’t remember what Ford called it and was too lazy to look it up. 
Thanks Again
Chuck
If you are:
- adding power (or plan to someday)
- want the bigger brakes that are generally on the 9"ers from a 69-70
- want more aftermarket support in terms of avail. ratios
I feel it is worth it.
I have one sitting in my garage (with the spring perches) for just such a swap (with a 3.25 TL pumpkin to go in it). Haven’t got around to it (surprise, surprise), but it’s only been 7 years, and I haven’t added any power to the mill.
Personally, I will not upgrade it to 31 spline until I have a problem, but if you are looking for hard launches & need to buy a new center section anyway I’d consider it.
On the other hand, if your 8" is fine, and the 9" you have will take cash away from other, more pressing issues, I would just let it sit, or sell it.