A couple of rare Canadian-exclusive options for a change.

How about RPO Z46 - Cold Cranking Equipment. Not offered in the U.S. AFAIK. It was offered on 1967/68 Canadian built GM cars, and maybe 1966 as well.
It consisted of a H.D. 70 amp/hr battery (T60), a 12-42 ampere "Delcotron" (K79), H.D. Battery Cables, plus an Ultra-High Starter.

Another obscure option that may or may not have been briefly available in the U.S. but more readily accepted in Canada was RPO C47 - Auxiliary Under-seat Heater. The heat hoses are T-d at the firewall and a set of hoses run in the trans tunnel to a separate 2nd heater core under the seat sealed into a cut-out the floor. There is a 2-speed blower switch on the bottom edge of the dash. Not common in cars, it was more like something you'd find in a school bus.