They are 10x32 thread...
Mine front one measures 0.44" and the rear one measures 0.80"...
I don't know if a regular machine bolt in that thread size will work or not. It can't be any longer than 0.80" or it won't tighten up...
A tad shorter would be better...
You can find them at hardware stores, if any still exist, or Trader Horn or Tractor Supply stores...
Maybe even a local gun shop...
That is a fairly common size so you shouldn't have a problem...
Good-luck...BCB