Hey 78, they're 4" X 10" with big beefy magnets!
The GM RPO numbers apply. The Part number for the rear speakers I'd wager to say would likely cross to a Chevy light truck RPO and PN as well.
G Audio System Speaker, Rear.(UP8)
1976 - 1992 RPO U64 4 speaker standard range speaker rear, #16034200
1976 - 1992 RPO U66 4 speaker extended range speaker rear, #16040950
There are other systems listed, but that part number covers ALOT of years. you could measure any rear speaker in a GM car, truck, or Van with rear speakers same # from those years. Left and Right are the same PN.
However. lucky for you I've got my rear air all apart. It's only 4 more screws. stand by... See above. Gday!
Last edited by Wedgy; April 02nd 2019 6:48 pm.