Yes, Red Caboose used the basic Atlas drive under the GP-9 shell they developed and sold most of those as complete ready-to-run units, both in scale and three-rail.? They were pretty expensive and apparently RC lost money on?the project.? They sold quite a few of the shells as kits afterward.

P&D under Pat Mucci had serious visions for O scale locomotives.? After Kemtron effectively went out of business P&D bought the production fixtures for their GP-7 and RS-3 (after an intermediate owner--Railtex--produced the stock kits and sold them with CLW drives) and began serious upgrading; initially the upgraded GP (offered in the several phases as both GP-7 and GP-9) used a CLW drive but eventually they developed their own first-rate drive, based on Weaver components (after Weaver replaced theirs with cheap China crap drives to allow space for three-rail electronics) and with the excellent lost-wax Blombergs from OCS in Korea.? Incidentally, the P&D upgraded kits stopped when Weaver introduced their plastic RS-3 (and later the RC plastic GP-9's), as the P&D brass kits were excellent but necessarily expensive and required soldering skills to assemble.

About the same time P&D got access to Atlas F units—I've heard the Austrian government refused to allow the export of the dies—and improved the detail, so that various F types and phases of each type were represented (why Atlas thought an F-9 was a better choice than F-3's or F-7's is something no one seems to know).? By the time P&D had developed their improved version of the Weaver drive it was also modified to fit under their improved F shells; the P&D drives for the F units and the GP-9's are configured differently, even though they use the same components.

Almost certainly more information about O scale diesels than anyone wanted to know.

And, yes, the original Enhorning drives left MUCH to be desired; the Port Able after-market scale conversion drive for AF (later bought by Beveridge) used Enhorning sideframes.

Jace Kahn