Back in my HO days, I had 2 of them, An E8 and an SD40.
Both had 2 powered trucks with 2 of the 3 axles powered. they had an OK moter, however, they were not equipped with flywheels.
The best slow speed was around 5 SMPH and the top end was around 150 SMPH. Both ran OK and I got about 4 years service out of each before I sold them off.
Detail tended to be quite heavy and the couplers were truck mounted with that "Toothless Grin" in the front and rear pilots in the SD40.
I felt that they were much better than the trainset quality units put out by Bachman, Model Power, and lifelike (Proto NOT included), and were about on par with the Mantua line of Diesel locomotives, both which are a big step down from Athearn.
That aside, I have heard of modelers doing wonderful things with them involving re-motering, kitbashing and super detailing and they can be considered a "Diamond in The Rough" it you are willing to put some time and effort into them.
Have a great one!
Terry