OK guys now that we bashed almost all the early brass here are some fixes for some of the early locomotives I can't say to much for HON3 I do most of my modeling in ON3 and large scale but for some of the older ON3 like Balboa C-19 an the C-21 and the SS C-16 I found that San Juan's new drive for the C-16they doing is probably one of the best drives I have ever used, it is installed easily and fairly quick has great slow speed qualities and is quiet. Coker can tell you that this is no bull but I'm presently redoing a Balboa C-19 to #340 at the speed it runs it would take about 2hrs to travel the 300ft. of mainline on the railroad and handle 10 cars up the 3% and not break a sweat.
I've also used this drive in SS RGS 10 wheelers and there C-16's the conversion in the Balboa C-21 took a little more time (outside counterweights) but was worth it. I've done one of the C-19 conversions for a fellow it runs on the Denver O scale layout in Union Station he loves it. With the price of todays brass it pays to bebuild some of the older engines. Anyway my $.02
Fred