The new engine types are applied to vehicles, but not depots, making the former impossible to build. This also applies to new games.
Thank you for the report - I think that I have fixed this in the latest version. (Makeobj and the pakset will need recompiling for the fix to work). I should be grateful if you could re-test.
Just tested, now it seems not only not to be fixed, but also that some depots and signalboxes are available throughout the timeline ???
Edit: Could compiling makeobj with or without SAFESEH have something to do with it?
Edit 2: Fixed it by recompiling the game.
Edit 3: However, vehicles of the new types cannot be sent to a depot.
Thank you for the report. I think that I have fixed that, too; would you be able to re-test? I should be grateful.
Fixed.