Athearn had units with both flywheels and geared trucks available before the SD9's, but they were options, the standard athearn F7 was a band drive with no flywheels, but you could get the flywheels and geared trucks for an extra cost. The SD9's made those features standard.
Thanks for the links and info - coincidentally I have only recently started looking into re-power options in general, had looked at NWSL and the 'Helix-Humper' but had not crossed A-line before. They have an interesting site! Lots of goodies there - I wonder why they are so out-of-stock on their complete running chassis? Regardless they look like they do quality stuff. Again, fascinating info.
I think the problem with A-line is that the chassis aren't massed produced and the current generation of RTR has largely curtailed his business model. Personally I wish we still had more shells and custom frames, but alas.
Less modeling and more buying seems to be the trend. I'm tempted to grab one of his chassis just to have one before they're no longer offered. You can still build your own from parts, and I'm considering getting some of the E truck sideframes. Prices are a little steep compared to some other sources....
Just as a postscript to what started this thread in the first place - an old Rivarossi E8 that I had picked up to convert to a dummy, but lo and behold actually ran decently but with ZERO traction to pull anything without sitting there spinning its wheels - I managed to shoehorn an Athearn F7 'super weight' into it today. It works! It's not going to put anything else to shame, but it will pull a dummy E8 plus 8-9 streamline cars without any drama. I'm still intrigued with the idea of mating a Rivarossi E onto an Athearn chassis and making it look like it belongs there - but this works for now.
