I believe there's an Onan that's a small 2.5k or 3.5k diesel unit. I'm not sure but I think at least some tunnels won't let you go through if you have propane tanks in the vehicle. The diesel would be my choice since I'd be stopping to fill up with diesel anyway. Propane would at the least add another time penalty at the J or wherever you filled and at worst would require a detour to a different facility to fill on top of the added time. Good luck with whatever you decide on.
Leo Bricker, owner trucks 3034, 4958
OOIDA 677319
73's K5LDB
Highway Watch Participant, Truckerbuddy
EO Forum Moderator 1+ Years of Service
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Support the entire Constitution, not just the parts you like.