What in particular would you like to know? They were a good machine, they were B/C's first tracked machine, built on the 863 design machine, very solid.
Deutz engine is good except for the occasional head gasket, keep the timing belt serviced.
Track drive motors gave some trouble, lotsa $$$ when they went bad, of course tracks are expensive as are any.
Kept the 864 number mabye 4-5 years then went to T200.
Good luck with it, at least there is no chains, axle bearings or seals to contend with.