U-Joint sizing

[geffen928]

Evening Gents.....I was getting ready to order my new 489 case from Dr.Diff.  It gives me the choice between either 7290 or 1350 U-Joints.  I wasn't sure what I had on my car from the factory.  I measured and my existing joints measure 3 3/16 x 1 1/16 diameter.  This seems much smaller than the 7290s or 1350s.   My car was originally a 383 2bbl A727 car.  Do I have a light duty drive shaft??  Your thoughts??

Geffen

[Eldovert]

You should probably size u joints to your intended power output and use..healthy stroker and four speed?  go big.
Stock rebuild and 727..original size is fine.
Cheers,Pat

[John_Kunkel]

You have the 7260 u-joint, you can get an adapter u-joint to mate your 7260 shaft to a 7290 u-joint.