Hondarider,
I would say no, most tractors that I am familiar with one reservoir for the transmission and hydraulic fluid. I other works they all share the same fluid from the same place. you just need to make sure that the 3pt is lowered, bucket is lowered so that all available fluid drains back to reservoir.
Got any pictures? We had an early Kubota for our lawn business that was the smallest they made at the time. It was a beast! I love old stuff. Pictures would be great!