I have 580b 1975. I have changed all filters but one. There is one near bucket control not sure what filter it takes . I tried taking it off couldn't get to move. Most of the filters appeared to have been on for awhile and were hard getting off. I'm afraid I'm going to brake something if I put much more pressure on it. Any ideas type filter and how to remove.
That's your hydraulic return, it should be accompanied by a pressure gauge. I believe element is determined by shuttle type for some reason.
Early in that design hydraulic system ( probably in the 530 series) there was a much shorter can and filter, I would think that a B should have the longer can and filter. The standard and power shuttle used the same hydraulic filter to my recollection. Mel