If you don't know which filter is which, let me assure you, you will know if you have the wrong one ready to go back on if you take the Hydraulic Suction filter off. They are NOT interchangeable at all. I liken my experience to the monkey trying to put the cork back in. I figured out on my first 50H service attempt on my LX2610SU, that it's smarter to just go ahead and drain the fluid via the drain plugs. So, I had a second and much more successful service procedure on the second try. You have a lot better control of the oil that REALLY wants to come out of that transmission. It just simply doesn't want to be in there any more. Someone posted a rather humorous description of the preparation for a colonoscopy in another thread. Pulling that suction filter off is not much different from effects of the industrial grade laxative given for that procedure. It isn't very nice when your tractor is behaving like it just drank 16 quarts of liquid dynamite. It will purge itself, all over you, all over your floor.
Both filters are actually below the top of the fluid level, and both will 'bleed' if removed without some ingenuity applied, or without draining the fluid. The HST (Transmission) filter can be changed by pulling a vacuum on the transmission case with a shop vac. Use a clothes pin or something similar to pinch off the transmission vent for a slightly better vacuum. This will minimize the 'bleeding' from the HST filter. If you're changing the Suction (Hydraulic) filter, I'm not sure that will help. You're basically opening up the main vein to the heart of your tractor. Good luck with that. In less than 30 seconds, I lost a gallon of very expensive SUDT2. Your safest bet is to keep a dedicated CLEAN drain pan for the SUDT2, and use a funnel with some kind of straining/filtering capability to put it back in. Don't use the same catch pan for motor oil unless you're just capturing it for recycle. If you don't want to put it back in, that's OK too. Just keep in mind that SUDT2 is just over $20/gallon. The LX holds just over 4 gallons (15 liters).
What I learned about the OM for the LX, is that it is WRONG about which filter is who. The instructions for changing the HST filter have a diagram showing the Hydraulic (SUCTION) filter. And vice versa. You can imagine my dismay when the HST filter that I had carefully prepped to be able to put on quickly would not fit while my brand new tractor was puking all over me like a newborn baby that ate too much. If I'd had the right filter prepped, yeah, I probably could have done it without losing much more than a half gallon or so. That was my plan. I read, I studied, I thought, and I STILL got it wrong. I'm a firm believer that when all else fails read the instructions. This time, I read the instructions first. That was my undoing.