Speed Pro according to "Big-Block Chevy Performance" by Dave Emanuel. HP Books 1995 page 16. A book from my bookcase. I should have looked there before starting this thread. Also, upon taking the rod off and cleaning up the underside, TRW is forged (not stamped) into the piston. So, I'd say I have a pre-'95 forged Speed-Pro piston (as per the above book) from a TRW raw forging (as per Pat McCarthy).