Yesterday, I finally found the exact replacement bolts for the ones that came with my Ford Racing/Performance driveshaft.
I've been searching for weeks, Googling, coming up with basically 2 options, factory bolts or Dorman.
The Ford Racing shaft comes with 6 new bolts, 2 black one size, and 4 Allen-head silver bolts, a different size.
Looking at some pics I had taken of the driveshaft before I installed it, I saw the Dana Spicer part number on it (who actually builds it for Ford), then Googled that, then searched on Dana's website and found the 2 part numbers that I was looking for, 128744 and 2021570.
The only place I could find the fkn things was on Summit's website, and the one I wanted 4 of was $8 each, lol.
Shipping and tax later, I'm at over $51 for 6 new bolts.
And why? Because I was an idiot when I installed it and didn't clean the threads in the rear flange before screwing in the new bolts, and I had a very hard time getting them in. Not sure they fully bottomed out, that they're fully tight.
So I'm gonna back them out, clean the threads, and replace them.