It is leaking oil from the top of the left side drive motor he has a John Deere z920A. If anyone has one and know how to take the left side drive motor with out taking out the whole trans-axle please tell me!
Most likely this is a version of the Tuff Torq 787Q0624220 Transaxle. There some variables so the serial number of the transaxle is important for looking up part numbers. But following two are common ones.
Or it can be the seal plug. PN 187T0136300. I seen several crack through and leaking.
Btw the Tuff Torq input seal is PN 187Q0624200 (TC15x42x8)
Also the oil will need to drained thru the filter by removing the cap. This is on the rear facing side of the unit.