ACK I agree, the 153 4 cyl. was standard on the P series, but you could C.O.P.O. if your heart desired into a C series. If they were willing to install a 348 as a C.O.P.O why not a 153! In none of my literature does it mention a 4 cylinder in a C series. There is mention of an Max. Economy Equip.
Along the same lines, I once boosted the battery of a 1989 Chevy pickup, 4 cyl. with Air Conditioning. The owner explained that the dealer recieved the truck that way and that she got it for a great price. Totally gutless as she explained but good on fuel. lol
RPO sheet from 1963 shows the L engine options but there`s no 153 in C series.
1963 Order Form
1963 Chevrolet Truck Engineering Features
1966 Order Form
