I purchased some drive parts from Lou at the "new" CLW when they first opened in California. I felt that their sprockets, gearboxes, transmission tower and U-joints were a little sturdier and better quality than the Weaver / P&D stuff. For one example, I'm pretty sure their upper sprocket was 10 or 12 teeth (Weaver used eight), and that was the one most prone to splitting in my experience. Their axle gearboxes were 10:1 self-locking worm and a similar form factor to the Weaver / P&D boxes.
If you're really going to pull 45 cars with one loco, you should probably consider using a dual-shaft motor (or two motors), and two transmission towers so all of the torque is not going through a single chain.
A newer approach is to use 1:1 back-drivable gearboxes on the axles, and obtain all of the reduction through a central tower, or through use of a 19:1 gearhead motor. The 1:1 boxes are heavy-duty 0.7 mod gears, and designed to handle heavy loads. My $.02.
