I replaced every drop of fluid in my WD this past summer. Bought a 5 gallon pail of universal trans-hyd fluid and used all but about 2 qts. There are just three drain plugs, the one by the PTO on the housing and the one on the bottom of the PTO drop box drain the front part by the hand clutch. The one under the rear end only drains the differential and rear portion of the tranny. Be sure to open all three plugs to get all the old stuff out. I found it easier to remove the battery box and access cover over the hand clutch, you can just dump it in and it will flow to all parts of the tranny and rear end at once, and it's easier to see whats going on. It takes some time for the level to equalize as it flows through. Remove both fill plugs and fill until fluid runs out fill plugs. Final drive pans need to come off, there will likely be thick sludge in the bottom that needs to be wiped, (scraped, scooped) out, then fill to plug level. As far as hydraulics, use same fluid as tranny, check level with lift arms up. Finals I used 85W-140 gear lube.