Okay guys, problem has been solved. The forward set that was on the donor car was pretty badly rusted together. The stud came out of the cylinder head when I tried removing the nut, as the steel nut was rusted to the steel stud. It took a lot of Evapo-Rust, anti-seize spray and heat from the torch but I finally got it apart. I then reconditioned the two brass washers and two castellated nuts by soaking everything in Evapo-Rust overnight, which got rid of every bit of rust on the nuts. When the nuts were clean, I hit them with the brass brush to finish the job and then treated them to Rust Prevention Magic to keep the corrosion from coming back. The brass washers cleaned up nicely too. See before photos above and after photos below, which also show the incorrect fasteners before removal. I then removed the incorrect nuts and washers on the front and rear of the exhaust manifold, installed the reconditioned nuts and washers, and torqued them to 10 ftlbs. according to the FSM. So for the first time in many years, I have the correct fasteners on my manifolds and I'm a happy camper!
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