Plash. I'm not really into American cars, only my '66 E Type Jaguar and '53 Ferguson TEA20 tractor, both built in Coventry, UK.
There is a very health vintage car and parts market in Australia with new "barn finds" fairly common. I recently saw an immaculately restored V12 side valve Continental "Zephyr", found in some farmers barn in reasonable condition.
Noncom. I passed on the links to stovebolt.com and hemmings.com - thanks. Not sure about commonality of parts, it seems most pre war GM vehicles, both ex US and ex UK (Vauxhaul) had Holden bodies or were assembled by Holden, until GMH commenced Holden car production in 1948. Now it seems, GMH are exporting Holden Monaros to the US where they are re-badged sold as something else!