I will probably never sell my 1969 Grand Prix with 92K mi, but I drive it so little and since 1986 I put only 15K on it. It will probably never hit 100K. What I like most is the driving position and its now-faint GM exclusive smell after it sits in the sun a bit. You cannot get that angry Rochester 4MV sound without a V8
The convertible Buick that Adam posted is also of that great Era, which IMAO ended with the rust-prone 1973 models. Even into the early 70s, GM made some great-feeling road machines, X-body Vega the rare exception. The 455 may not have been efficient, but because it was overkill, tended to last longer than smaller V8s
GM was first to redesign to ugly with few exceptions, Ford was the first to drop compression ratios on '71 models , heralding the "pooch era" and Mopar "experimented" with non-water-proof electrical wiring and fuel systems with dysfunctional, smog-addled carburetors
As for a "truck" vehicle by GM, Bell Telephone used to have an odd green and white two tone Chevy vans (not good in snow). I always like the Corvair van, 1961-64 called the Greenbrier. Could you deal with the air-cooled H6 engine in your extreme cold tho?