Some of them have a spin-on filter behind your left foot. I had an older model that had a intake filter on the pickup tube in the sump, had to pull the rockshaft out to get to it. When you say slow are you talking about the SCVs or the 3pt? These older tractors are a lot slower than the new ones to begin with, but my old man has an early 5000 with a loader that takes about 5 minutes to lift a roll, he's too tight to buy the parts to fix it.
cfpinz