Dear Chuck, Bill, Loren, Walt, Jon, and mid-60s Buick parts hounds,
I checked the parts book.... it varies by year. The 64-5 1366537 is also used by Olds for 1965, and is a replacement for the original 1362260 used in the 1964.
The 66-67 1369335 was superceeded by the later 69-72 1231283 piece.
The 64-65 1366537 was also superceeded by 1231283 in 1974
. . . . . .
Thanks Walt for taking the time to assemble the sequence of events in
"da' crime." Thinking about when GM superseded these parts, I started to wonder if GM itself was to blame for the less than perfect fitting parts. I suppose that the original inventory of 64-65 and 66-67 parts was eventually depleted. The "right" thing to do was have more manufactured. On the other hand, if GM had a part that was "close enough," they could substitute that for the dealers and suppliers. By 1974, some of these cars were 10 years old. At that point GM was probably itching to get people to buy a new car and didn't mind if the repairs weren't has nice as they otherwise could be.
When companies decided to make reproduction hood bumpers, they poured over the GM cross-reference books and picked the part that was most common to reproduce. They certainly didn't check every possible classic GM car to make sure it was a good fit. So the reproduction manufacturers might have been victimized by General Motor's own desires to cut costs and move inventory many decades earlier.
Cheers, Edouard
P.S. I have the CARS bumpers but it is an especially busy weekend with Mother's day. I'll try to get around to photographing them sometime next week.