I use Mystik jt-5 trans hydraulic fluid rather than the super expensive Hy-Tran fluid from the Cub Cadet dealers. Mystik jt-5 trans hydraulic fluid is not cheap . I use it in all my older Cub Cadet garden tractors that have hydrastat transmissions. TSC normally handles JT5 in gallon jugs and sometimes they have it in 5 gallon pails. I believe that these older rearends (transaxles) were made by Sundstrand.