I love my NJT AE-20! It has a lot of the stuff that I wanted to put on the 10 before I found this one. Clifford already mentioned the Cor-Ten steel to keep it from rusting, level floors, stainless, and pantograph doors.
In addition to that, the driver area is much higher than stock which brings it closer to floor level. Lots of Eagle owners make 'high drivers' but the AE 20 is sort of a factory high driver although not totally even with the passenger floor. We get a 748 trans instead of a 740. Comes standard with a hydraulic fan setup and power steering. Some consider it a good thing and some consider it a bad thing, but the AE-20 is completely wired with white wires with black numbers on them. The good part is that the number appears every couple of feet. The bad part is that when you look at a bundle of wires, they all look the same at first glance! From what I am told, the fuel tank is 165 instead of 125 on standard Eagles.
What else? Oh yeah! All AE 20s as far as I know came with 24.5 Alcoas.
A few bad things that are easy to change or live with. The fuel filler is only on the curb side instead of on both sides like most Eagles. No tach or fuel gauge. Have to pull the huge A/C unit unless it has already been done. 3.73 rear gear could stand to be a little taller.
That's about it. Did I mention that I love my bus?
I don't know Luke at USCoach, but the best source for Eagle 20 info (especially NJTs) that I know of is Norris at Jefferson Truck Parts in OKC. He was around when they were being built and can tell you anything you want to know. 800-813-9367
Both Norris and Silver Eagle Manufacturing have manuals for these buses. http://www.silvereaglebus.com/