Bob, I am going for the "used" look, so I appreciate your comment.
Chris, thank you! Every build is a learning experience for me.
Ruben, thanks! Watching your builds (among others), I think I've finally found the method to painting after assembly. The tracks and lower hull were painted with cheap flat black spray paint, mostly as a primer, but to cover up they grey. I then used Model Master Track Brown, mixed with lacquer thinner to spray the tracks. I was sort of careful around the road wheels, but figured touch ups would be in order. I hit the road wheels with the upper hull base color to make them green again, but I'm liking the fade to black method.
I am going on a field trip with my wife today, so no progress, but have the weekend off and plan to knock some more out. Thank you to all , please check back!