...can easily get up to 80MP? I don't know if its just me, I have experience with cars but not diesel trucks / vans etc. Mine is a used diesel v 8 u-haul like vehicle with a 17 foot box. I can drive it just fine and in reverse but I don't feel the trany shifting or i don't hear it shift at any rpm, but somehow i go from 0 to 80 mph no problem or overheating. We have driven it for at least 4 hours like this and seems ok. Any suggestions?