All Mopar cars made from roughly ’78 and up came with the “7260” joint.
All 8¼” FMJ differentials are the same, except for gear ratio (which can be changed).
Some came with 11” drum brakes and some came with limited slip
They did put a few 727’s in J bodies, but not very many. They did put 8¼”s in J bodies, but not very many.
The 904 family transmission can take a lot of horsepower, more than you are applying. Some prefer it sense it is lighter than a 727 and 1st gear is a better gear ratio.
Measurements of shaft are Center of Universal Joint (or U-Joint in short) to Center of U-Joint on the other side, sometimes referred to center eye to center eye or C.E. to C.E. Tube diameter can make a difference as well as U-joint size (in your case a “7260” which is standard (only option) for your car.
Transmission slip yoke diameter is larger for 727/833 as well (again, not a factor here).
Note: Chrysler calls the shaft from transmission to differential a “propeller shaft” and they call a driveshaft, what many of us call axle shafts. If you were to walk into a dealership and ask for a driveshaft – you will not get what you are expecting
There are lists of shaft lengths out there, but I hadn’t seen a list online for ’75 and up cars – except for an interchange company by the name of Hollander, which sells (massive size and expensive) books and software that will tell you just about anything you want to know.
I have a well-used book for vehicles made from 1964-74. Later year books are three times as thick, then it became available in digital format only.
In this case, I would measure your existing propeller shaft and I expect it to be about 1.6 inches longer than 52.5 inches. If so, then get yours cut down to 52.5 inches (or 1.6 inches shorter) and you should be where you want to be at.
When shaft is back, insert it into transmission as far as it will go (frontward), and you should have about one full inch before it seats into the rear yoke.
BudW
