Regarding the transaxle oil TT has this chart. JD has their own hydraulic oil, Hy-Gard- Hi (Low) viscosity. But TT dose not recommend the JD HyGard. Some JD tractors use the transaxle to power other hydraulic devices on the tractor. That is my take on why this discrepancy. If you do not use other hydraulic implements I would use what TT recommends. It is not clear exactly what the TT brand oil is but many think it is either Full Synthetic 5w-50 or 15w-50. The JD Hy-gard is 10w-30 as best I can tell.
You can ad drain plugs. You need two because there are two chambers. There are bosses cast in to the casing to make the drilling and tapping easy. TT has a kit to do this. You can also just get your own drain plugs. Unfortunately on most models you have to pull the unit to add the oil. On all units you have to pull it to change the filter and clean the magnets. The drain plugs allows you to drain it hot which is an advantage.
I also added a rebuild tip sheet from TT. I hope this is helpful.
You can ad drain plugs. You need two because there are two chambers. There are bosses cast in to the casing to make the drilling and tapping easy. TT has a kit to do this. You can also just get your own drain plugs. Unfortunately on most models you have to pull the unit to add the oil. On all units you have to pull it to change the filter and clean the magnets. The drain plugs allows you to drain it hot which is an advantage.
I also added a rebuild tip sheet from TT. I hope this is helpful.