was it happening before you changed tracks?
I could say the engine mounts could be ruled out unless you have to load the engine to get it to act up or they are just starting to wear enough when demand requires it to give a small vibration.
my guess would be more to the tune of worn seals/rubber getting age, tracks in windows getting worn, shrinkage of the seals, and any mild vibration is doing its thing. i would see if its worse/better on concrete vs a smooth flat dirt surface also.
my windows rattle your teeth loose in my wheeld machine but i know my seals/tracks in windows, engine mounts are all 15yrs old - mine is a volvo though so primitive cab compared to yours - heat only - just my side windows rattle not the front door.
do this, take a piece of foam, rubber, wood wedge, and put in the track or glass between where the meet etc.....or between the metal cage and the glass so see if you can quiet it down enough to hear anything else going on.
just some ideas to try to maybe isolate it and see if you can feel an inordinate vibration that is rhythmical to the track revolution/footprint, engine rpm, and troubleshoot
good luck