When I worked for the SP in the fifties and sixties all conductors were assigned cabooses. In Tracy we had some with single digit numbers. Almost all were two and a few three digit numbers. There was a caboose man that had the keys to all of the cabooses to clean and supply them. All were wood until the Feds outlawed them. The only exception was the BSM out of Roseville. That one had a caboose was a steel sidewinder. The crew that caught the job went to Fresno and there cab followed them down. We also had a number of tramps for extra jobs and seasonal locals (Firebaugh & Los banos). Most of our cabooses were built in the early 1900's. We always liked the wood cabooses better as they were quieter than the steel one and warmer in the cold weather.