The Wheels of Time models are fairly simple. They consist of high-quality resin castings that appear to have been mastered using CAD and 3D printing. There is a minimum of parts: single "body" casting plus left and right treads and exhaust. An optional blade and hydraulic cylinders are available as a separate enhancement. I opted for just the dozers as even those push my late 1951 era by a few years, but they looked too good to pass up (I am hoping that when the prototype police visit, they aren't as well-versed in dozers as freight cars!) The hydraulic blades weren't adopted until 1960 (the blades were operated by cable and winch prior to the adoption of hydraulics.)
I paid $22.50 each and also ordered one decal set for $7.00. They were ordered via a pre-order program. Wheels of Time is currently accepting names for a wait list for follow-on orders.
I will build up the pair that I purchased and provide details here. Stay tuned (it may take awhile, though, as I have no shortage of projects...)