The more important question should be, "When and where was the fuel pump made?"
If you're comparing two new pumps, don't. They're all junk from China and will not function properly regardless of the arm style.
Look for an original pump or a replacement pump built or re-manned before 1990. Have it rebuilt by Then and Now Automotive.
My 216 uses the 3 piece riveted arm.
I should point out that one of the new pumps I installed on the engine failed in about 300 miles. Upon inspection it could be seen that the three metal arms were not riveted together properly and only one of the 1/16th" pieces was actually contacting the cam. I dug out the original pump and rebuilt it over 6000 miles ago.
1950 Chevrolet 3100 (Ol' Roy)
1939 Packard Standard Eight Coupe (The Phantom) | 1956 Cadillac Coupe de Ville (The Bismarck) | 1964 Ford Galaxie 500 coupe |1966 Ford Mustang (Little Red) | 1969 Pontiac GTO (The Dishpit) I 1979 Ford F-100 | 1976 Ford F-150 (Big Red) | 1995 Ford F-150 (Newt)
