It's a Tuff Torq K71A.
I just traded my old 325 of 22 years due in part to an oil leak from the shaft that is connected to the hydro pedals.
In my research on line, I only found a couple of similar problems. Some described once getting into it, the case was too far gone, negating a rebuild. I did find some used units on eBay, but felt this path too dicey for my comfort.
In talking to the dealer prior to trading, I found that not all parts are currently available. A complete new unit is $3100 (ouch).
I figure the X584 I traded for will be the last L&G tractor I ever need (I'm 63). I figure I deserved it (LOL!)