What modifications do I need to do to a transaxle?

I just started my first mower build. I did a pulley swap and drove it around a little bit, but I noted the transaxle was getting hot and I want to put gear oil in it. How would I go about doing it? Do I need to put special seals in the tranny for the oil? And how should I get the oil in the transaxle. Also, are there any "must do" modifications that I have to do to my mower? Thank you

I put gear oil in mine by taking the case apart. I left the old grease in it and just added the oil, about 2 cups to make a slurry goo to ooz around. Probably not the best thing to do because of the type of grease it was that it doesn't mix with oil too good(That bentonite grease I think it's called). But I don't run mine fast either. As long as the original seals are OK, the oil shouldn't drip out the axle shaft seals. And silicone the case halves together.

A good start is to let us know what kind of transaxle you have.  That helps us with helping you a little more.

The tractor is a late 80s craftsman and it has a Foote 4150-46 transaxle.

I'm sure some smart guys are around, hope they chime in.

Not sure how fast you are going, even with oil, the transaxle will get hot.  My mower's spicer under normal mowing duty gets hot.  I know you want to convert to oil.  Depending on how fast, you typically do not have to.  It will probably leak a little oil on that trans as it does not have oil seals on the end of the shafts to my knowledge.  I'm thinking FELT.  Not sure if you can replaces those with oil seals from a MST (Tecumseh 788088A) or not.  A big thing to consider if you are going to replace with oil is, you will need to be able to vent it when it heats up.  Some have to drill a hole and install a barbed nipple and run it up typically under the seat with a fuel filter on the end.  Not sure if you have the neutral safety switch, sometimes those can be removed and use that location.  Hope this gives a start.