Yes, they have filters. So, ALL the oil will drain from there, thats good. My only remaining thought is the filter guard screws are to be torqued to 115 and the top port plug to 120. If its really necessary to torque to those levels, if I can't manage that level I suppose a cheater pipe would work.
in ALL THE YEARS (DECADES!) I have serviced Hydrostatic Motor Drives I have NEVER used a torque wrench to install filters OR top filler plugs! EVER! You are talking about using a "cheater" bar to install filters and a plug and red flag warning bells going off in my mind! Read the service manual again please. Are you sure it is not INCH POUNDS? ...because it sounds like the use a cheater bar would be for some torque spec so high in the foot pound range that would require huge amounts of force. I find that very very very UNLIKELY. The last thing you want to do is make a mistake and go king kong with a cheater bar and bork up the aluminum threads. So please for the love of all things good and right, please refer to the service manual and not some online forum or youtube video dude telling you some ridiculous torque value requiring a cheater bar. It is most certainly NOT in the foot pound range and NO cheater bar would be necessary to tighten the filter and top bolts! Read the service manual ...
here is what I have ALWAYS done: hand tight...lightly coat the rubber seal on the filter with oil and hand tight, same thing with the top bolts. Hand tight. With the hand...no torque wrenches needed to do this.
there are basic things you will always want to do to prevent damage to the hydros when doing lube changes. I will list several tips that apply to all hydros I have ever serviced:
1. always lift the back wheels...on blocks for safety. I put the entire mower up off the ground, with the rear wheel where the hydros are located pitched down...gravity is your friend when you want to drain the lube...just makes the process easier this way. The key is safety. Because you are going to be starting the engine, sitting on it and running hydros after the oil change! . follow the service manual after the oil is changed...I LISTEN to the sound of the hydros during this air purge procedure...at low engine rpm...then as the sound changes, increasing engine rpm! You can hear the sound change. At first you might hear a slight squealing sound from the hydros....this squealing sound should go away as air is purged. Move the controls SLOWLY. Do not rack them back and forth like you are trying for gold in rowing. Make sure you move the steering bars back and forth and then one forward and one back motion...many many times. The service manual should show you the motion required. I do this for at least 2-5 minutes. THEN I turn engine OFF and let it sit for 10 minutes, grab a cold one, and then I look for leaks. A sheet of paper below the filters and filler plugs/bolts helps to find leaks. Fix any leaks...meaning simply hand tighten again.
2. The service manual should also show exactly how much oil. HOWEVER...AND THIS IS KEY. There will always be some oil that does not drain. So if you go by the service manual, which assumes the hydros are completely empty, then if you fill with the prescribed amount, then you will be overfilling..and that is not good and will damage the hydros. So What I do it measure how much oil drains out. It's a simple thing to do. Then THAT AMOUNT is how much I add. No more. No less. On some hydro systems, there is a reservoir and a min and max fill line. This is usually a COLD FILL LINE. Remember this when replacing hydro. Make sure the hydros are not hot when replacing oil to this line. Follow the service manual.
3. If you don't know what an equivalent hydro oil can be used, then use exactly what the service manual prescribes. (alot of people get confused about oil equivalents...so if this is confusing then just buy exactly what the service manual states). No need to become a rocket surgeon and use specialized oil additives. Just use the correct hydro oil per the service manual.
4. Clean the cooling fans. Just soap and water...since you are working in the area, its a good idea to clean then up..make sure there is nothing twisted around the cooling fan shafts and that the entire hydrodrive body surface is nice and clean...this helps remove debris and grime that can cause problems allowing them to run as cool as possible....I use simple soap and water and a small plastic brush... I do this after adding the hydro oil. This helps identify leaks during the purge test. If you have drained oil all over the hydro drive and machine will confuse you thinking you have a leak.