Personally, just pull the 3rd member, have it rebuild with a posi and what ever gears you like. 3,25 or 3.50 are good on both street/highway.
Or just order a new one from Currie, Summit, etc.
That is the eventual plan. If Nancy comes through with some additional stimulus, it might be sooner rather than later!
These threads can drift a bit from original topic. I was originally just looking for confirmation that a change in rear-end gear causing a speed-o change which was answered. Then some how there started an 8" or 9" rear-end. I was always pretty sure, and still am, that the current rear end in this car is an 8". What it was born with, who knows!?
It was born with a 9", every 1969-1973 Cougar was. That is a well established fact. Whether you have an 8" or a 9" rear does have some relevancy here if you are thinking of changing the gear ratio. It would be nice if you were to purchase the correct fitting parts to do that change. Did you look to see if the ID tag is still on your rear?
WE know. You came to the experts and got expert advice, yet you continue to question it. If you don’t believe us, maybe do some real research (using source documents - tossing out question on the internet is not research unless you know & trust the source).
Have a nice day.
(weeps for the future)
PS: stick your location in your profile, maybe somebody close to you has the parts you seek. Not at all unusual for a Ford guy to have a spare 9" or two laying around. I have one under my workbench (from a '69, 28spl w/a 3.25 posi).
PPS: the picture you posted is an 8". You can pull the casting date off the 3rd member if you feel like you have a mystery on your hands. Pretty common back in the day for folks to go w/highway gears once the gas crunch hit.
Sorry if my comment hurt your (or the collective groups) feelings, you confirmed it is indeed a 8". That was my only point, I have an 8" and that’s what I already new I had, that was never a question I asked of anyone. Some one else asked or brought it up.
I really don’t care what the car was born with, if you say all cougars came with 9", I have no reason to not believe you.
But with that said I’ve been told inaccurate information on this site before on other topics by other people, so I ask questions on different platforms, research vendor sites, among other things, and come to my own conclusions.
Don’t think you hurt any feelings. I think what Chris is getting at is there is an easy way to tell exactly what your car was built which was posted above. I think your posts just reads like your still questioning how it was built. That’s a mute point since you know what you have now and who knows how it got there.
Now the bigger question you have to ask yourself is what are you going to do about it?
Sorry to see this thread head off in the direction of the famous “Welded Distributor” one.
Quick Performance in Ames, IA is a great supplier of both 8 and 9-inch axles’ third members custom built. Want 3.40s with a Yukon Grizzly locker? I got one. Great sharp guy.
The rear end parts I can’t get for free from work I’ve purchased from Quick performance and agree he is good and knowledgeable to deal with. The 28 spline 8" and 9" share the same axles and axle bearings.
BTW, I am replacing the 3.25:1, traction-lok, 28 spline axles 3rd member that I have now with the 3.50:1, Eaton Locker, 31-spline axles it originally came with. So I may have a spare 3rd member. It has zero miles since rebuild and I paid $925.00. Your mileage may vary.
