I'd park the new car in the driveway and park the truck dead center in the garage so you can work on it. Space heaters can warm up a garage pretty well.
I'd start the truck up weekly and let it run for 40-60 minutes. If there wasn't snow on the roads, I'd drive it somewhere.
When the truck was in the heated garage, did you go over there and start it up every week? Heated garage or freezing cold garage, the truck doesn't know the difference.
1950 Chevrolet 3100 (Ol' Roy)
1939 Packard Standard Eight Coupe (The Phantom) | 1956 Cadillac Coupe de Ville (The Bismarck) | 1964 Ford Galaxie 500 coupe |1966 Ford Mustang (Little Red) | 1969 Pontiac GTO (The Dishpit) I 1979 Ford F-100 | 1976 Ford F-150 (Big Red) | 1995 Ford F-150 (Newt)