I weakened and bought 2 more of the latest D9T's from the new producer of these models, Diecast Masters. Confirmed that they are the previous Norscot models, with what I believe is probably the latest color scheme, Caterpillar are using. A 2 tone yellow and black. Also answers the question of why one of those D9's on the train had a black blade. These now come in a very fancy tin container, within a quite plain, thick cardboard box (might only get that if mailed to you), a molded black foam interior surrounding the model in it's tin and a complimentary booklet, advertising the other lines. Of note is that there are a number of the previous HO types missing from the list.
My first thought was that it was a larger scale, because, alongside the ones I have stripped down it looks massive, the blade I was sure was much bigger. But actually placed next to the ones on the flatcar decks, it was just the fact that looking at the open front does make it appear so.
Anyway, a couple of comparative pics
These DCM ones also have an operator figure installed in the cab, which I won't need or want. I had prior to buying, stripped one of my other ones right down as far as I could get it by just taking out the 3 screws holding most of it together. 2 in the base underneath and 1 up inside the body that secures the motor housing to the mid section. Tracks get removed first, the stretch over the sprocket and wheels. The problem then how to remove the cab, which while able to be wriggled about a bit, wouldn't come free. Looking up inside beneath, I could see the protrusion that the 3rd screw went into, but directly in front of that was a similar blind one, which would suggest maybe another screw or locating peg for the cab or it's interior (there is a seat in the Norscot ones). The other thing that would prevent the cab being removed even if that is so, is the rollover protection bar over the cab's roof. That has legs on either side which connect to the track guards. Looking up under them, I believe I can see the ends of small dowel extensions from those legs, passing through the guards. Just what or how to knock them out will be the test of whether that rollbar can be dislodged without damage to anything else. A shame they don't seem to offer the model with or without driver.
When I begin this dismatling, I'll add pictures of how I did it (once I remember how I did them the first time)