What you smelled is the mercaptan odorant used in propane. A mercaptan is also used to odorize house gas. House gas-methane, ethane, butane, and propane are colorless, odorless, and tasteless, so an ordorizer is added so we can smell leaks. If you look at propane trucks, some will say "Odorozed" others will say "Unodorized". This indicates whether the mercaptan odorizer has been added (only about 1/4 cup per truck). Skunk juice is also a mercaptan, by the way.

The SP standardized on Waukesha eninators and ice engines, and in the 1960s, except for about two or three main line coaches, only the old 80-footer commute cars had axle generators (the gallery cars has diesel generators).