Private
I would push the weathering/drybrushing a little bit more.
For your consideration, (and this goes beyond your dry brush question - so I hope you don't mind).
Try taking a diluted black wash, and apply it to the corners, indentations in the hood, around brackets etc. Apply with a small fine pointed brush, and let the capillary action of the wash pull itself through and around the creases, brackets, indentations, etc.
You have yet to work on your tires, so weather those as you see fit.
You could also consider drybrushing some rust around certain areas of the rail framework and brackets, and some spill areas on the fuel tank.
For pure drybrushing, I would take your base coat color, mix in white, (approximately 50-50 base to white), and try drybrushing a bracket, or some part "out of the way" and see what kind of contrast it gives you. If you like it, continue on, drybrushing all your high points, i.e. handles, brackets, hinges, edges, etc, and see what you think.
Private, this is a good looking vehicle now, and only you can decide how far you want to go with additional weathering/dry brushing. Personally, I've always felt if you think you should quit where you are with a model, you probably should. There is always the next model to experiment with.
Good luck and please keep us posted.
Steve
ps: As an experiment, if you have some dunklegelb, try drybrushing a part, maybe under neath on the frame and see how this looks. If you like it, hit a few spots topside with it. I have found dunklegelb, when dry brushed lightly to many different base coat colors, gives a dusted weathered appearance that contrasts nicely with the rest of the model. Again, good luck.