Currier Garage in Holderness on Route 175 works on a wide variety of vehicles including old cars, new cars, trucks, buses, and utility construction vehicles. They have a very old Ford Model A that is used as a daily driver in Spring, Summer and Fall, and is not used in the winter due to winter road salt issue.
Currier has its own Ford Model A so it can work on antique cars from the 1930's.
Another place for antique car service is
www.ktmauto.com in Plymouth, close to Main St. It has a 1925 Buick Opera Coupe and a 1940 car which belongs to KTM.