You'd have to buy on the condition of the two tractors, but all things being equal, the 7475 by about a million miles.

DynaVT is a fantastic transmission, the best I've used. You don't state what vintage the 74 is, but it could have one of 2 perkins in it or the very last with the grey frames had the 6.6 Sisu, which is the pick of the bunch.

by 5500 hours, they should have had any teething issues sorted out and if everything is working as it should DO NOT GET ANY SOFTWARE UPDATES! If it's working, leave it alone!

One thing that is a pain is the cab suspension can get leaks. If the compressor is cycling a lot, you have a leak and pull the fuse out until you get the suspension bag things changed or it burns the compressor out. I think there was a mod to solve the issue.