[YNOBIL]

Originally Posted by azkeebler

Correction, there was no "F" blank. The corresponding trunk key for the "E" blank was "H". Made no real sense, but it is what it is.

No matter how or what GM did originally, the aftermarket suppliers don't follow the corresponding blanks used to their relative application. A non-GM reproduction '62 ignition cylinder will not have the B-10 octagon keyway.

To make things even more confusing, fleet vehicles (u-hauls) and police or government vehicles used round head keys for all their locks or exclusive blanks all their own. Even back in the '30's.

Thanks for the update. For some reason my GM Parts books only list the keys by year and didn't list the letter codes on the keys. Went down to my basement and found some new GM lock sets and keys. The 4th sequence was "J" Ign and "H" trunk. Also, don't know what year but at some point they started keying the doors to match the trunk instead of the ignition so a thief couldn't pull a door cylinder out and make an ignition key (That's how my 3 month old 72 GTO was stolen).
And you're right about fleet cars. Way way back in 1967 I had a job at the Ford Plant in Chicago installing trunk lock assemblies in new Galaxie's and when a Chicago Police Car came through there would be a special lock set for it.