i have a d5hxl , sat for 4 years, bought it ran it for about 100 hours and lost all of the frictions, i changed all of the fluids when i got it, the trans oil had just a tiny bit of water from condensation. turns out the friction material absorbs water and falls apart, about 15,000.00 dollars ( i had cat dealer do the work did not have time myself )
replaced them and have serval hundred hours without any problems.
the dip stick should be on the left side door where the battery disconnect switch is.
a picture from the side will tell us what shape the under carriage is in some what