That much fluid coming all at once may very well overwhelm a funnel. A clean drain pan with plenty of capacity might be better. Then it's just a matter getting it from the pan back into the tractor.....Thanks for the good ideas. I'll use some grease or gasket adhesive. The cover does need to come off to get to the o ring. Lots of fluid loss. Trying to figure out the best way to drain the new fluid back into the 1 gallon jugs it came in. Probably use a very clean funnel and make sure the area around the drain is wiped off clean.