Going by .RC's link D6H is close to a third of the weight lighter . Keep up ? eventually . Komatsu D65 would be better , D85 about the same class as your D7G , bit heavier .So, I've been wondering what would be a logical upgrade for the 7G that we got a few years ago. She has done alright for what we paid for her, but all things considered I think it would be more cost effective to look at something different at this point. Blade is shot, undercarriage is wiped out, engine uses over a gallon per day, and now the steering issue. Will a 6H keep up? Not trying to highjack the thread, just seemed like a good place to ask.
Komatsu D65 would be better , D85 about the same class as your D7G , bit heavier .
D6H more like a D5 , probably good idea to get another D7G and keep his one for parts . Komatsu not too bad for parts here , little things that make a dozer tidy like door latches not around any more , for mine anyway . Friend of mine got stung $10,000 NZD for a D4H radiator this winter , Caterpiller trying to remove older machines the hard way , he says he won't be getting another .Parts is the problem with them.
I do not know if older Cat elevated sprocket machines have the potential for more expensive issues then older dead axle design cat machines. But they are all expensive when things go seriously wrong. But as an example take the track frame. Does the cannon wear out? What about the pivot shaft? Does it bend/wear out? It has been said the D6H track frames had cracking issues the factory issued a repair bulletin for. I think the elevated sprocket machines are more rebuildable, and last longer, but at a cost. Rebuild one and you have a great machine for many hours.