Got the rear studs today. They were not exactly a "bolt in" the knurled dia was too long , and I had to turn then down and thread them, but it all worked out great in the end! I'm blessed to have a lathe and mill in the garage, comes in very handy!
First picture is from left to right, stock stud then the 560-287 Papco stud as purchased, then turned down, then threaded. I made a big rad on the lathe tool so as to give them maximum strength.
Second picture is installed studs with one stock stud for comparison