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Hi CH, The B transmission and PTO assemblies share a common lubrication sump and use the same lubricant. The hydraulic pump, if so equipped, takes it's suction from the PTO area of this common sump. The PTO gasket for a PTO equipped with a hydraulic pump has a continuous portion of gasket material across the bottom portion. That gasket then acts as a dam to partially divide the transmission and PTO sumps. This fact prevents the hydraulic pump from ever totally draining the transmission lubricant. The pump will be starved for oil before the lube is removed from the transmission area. The gasket for a PTO w/o hydraulic pump has no such barrier section and is just a normal peripheral gasket. A fact to remember is that if you add another hydraulic cylinder or use one with a larger diameter or longer stroke than originally supplied, you can easily starve the hydraulic pump of oil since the volume available to it is quite limited by design, especially with the proper PTO gasket. An interesting side note is the "official" lubricant specified for this area. Before hydraulics, the lube recommended by AC for both the transmission and PTO (same sump, remember) was SAE 140 gear oil above 32 deg F and SAE 90 gear oil below 32 deg F. The later recommendations for lube (transmission and PTO) with hydraulics was changed SAE 20W since the heavy gear oil was unacceptable for use with the hydraulic pump.  Rod
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