Hi LArry.
I had a similar problem with my old superchief. Check the tire pressure on the right side. If you dont have one get a low pressure (atv) tire gauge. Make sure all tires have the same amount of air in them. (1 pound makes a big difference when you are only running 3pounds of pressure. Also check your chain tensions. If one side (right in your case) is really cranked down, that may cause you to have a slight drift too. You should have about a half inch of play on all of your chains" pulling from the middle.
AS far as oil changes go, I get a tube and attach fitting to it that screws into the hole. You can do the same thing on the opposite side of the tubes by crimping a fitting with a cap to stop the flow. I then drain into a large tupperwear that I lay in the tub. Some poeple leave this type of device on the t-20 all of the time because it is such a pain to get to the drain plug. I hope this helps.
Famous last words: I swear honey... I am just going to change the tranny fluid. I won't tear this one apart...