You check the stalls in third gear. If it is good there, then all is good. I didn't know they had a lock up converter in a D65. As I recall on the machines I've worked on that did have that type of converter, they locked up on load and not engine RPM. The temps you are getting on the piping is not out of line with what I have seen on other machines so I'm not real sure if your problem is real or a phantom. I'd suggest taking an oil sample next to get a read on what is in the oil. Does this machine have an air to oil cooler or an engine coolant to oil cooler? Making sure the fins are clean, the belts are in good condition and adjusted properly and that there is no damage to the blades on the fan are some other things to check.