Mike B - If you overfill it, won't there possibly be leakage, at least from the input shaft end? Not sure what you mean by "as far as you can"??? Many/most of the SM420s didn't have full seals on the input shaft, just the "slinger" set up which is going to at least allow seepage until the oil level falls below the bottom of the input shaft
You'd have to get creative and seal the input shaft with some Plumbers Putty or electricians Duct Seal to try and keep the lube in the trans...note, I've never done this, but it seems doable to me
Or, you could sink it in a 55 gallon drum full of used motor oil...set the trans on a brick in the bottom so any water that gets in is down below the trans...
Mike B
