I bet that stair truck doesn't. Anyway engine 51 is the same as the normal engines in the mod only it's yellow. I think the best solution would be to create a submod containing lots of (New) LAX units, and remove them from the main mod. But in the submod, as well as the new vehicles, there are new missions and/or a new freeplay map which are all airport based. Then everyone is happy, you can have them if you want, and if you don't like them then you don't have to have them. And it's more realistic.