D2 common problems

I am looking at purchasing a D2 and I was wondering if there was any common problems these machines have. There is a lot of posts with a wealth of knowledge, but my eyes can't handle staring at the computer screen for hours. Just a little back ground on the crawler. The current owner has the right side track and final drive off of it. So I'm not sure if it had a stuck clutch or there is something bigger going on in there. He currently can't remember why they have taken it apart. He says it has been there since the mid 70's. I there is anything common to these that anyone knows of I would appreciate the input.
Thanks

Steering clutches stuck is the biggest one.

What serial number is the tractor. Later models (5U after ~13000 for example) are a few inches longer to allow the clutch to be removable without pulling the engine. An oil clutch was an option for the later models as well. Then there are things like 5 roller track frames and large diameter front idlers that make those machines somewhat better handling with a dozer than the rest of them.

I have one awaiting restoration and the clutch is jammed and it leaks a lot of oil from several orifices.

I have been told that the clutch jam is a common problem and caused by the locking pin/device (which I am yet to sight) failing allowing the clutch to self-adjust against the engine rotation until it jams - which mine is. This in turn causes the clutch brake to bind and heat up considerably - showering sparks into the clutrch housing - which mine does nicely, and then this damagies the clutch brake mechanism itself.

Apart from this and the aforementioned sticking steering clutches (which are a true PIA to fix) and the usual bashed-up or corroded panel work and track wear/gasket leaking issues common to all tracked machines, they are a truley wonderful machine😊

Don't forget the pony carb. If it has a pony and it has been sitting for a while, the fuel lines are junk and the pony needs a severe cleaning.... and tune up

Thanks for the info, all worth checking out before purchasing