I got a black light the other day as a last ditch effort and it popped the sticker out like magic! Turns out, the tractor has a swapped engine and a different deck. It's a 917.272201 25HP v-twin 46" hydrostatic transaxle DLT lawn tractor just like the ones at the shop. The motor was swapped for a near perfect date matched 20HP opposed twin. Mystery solved!
As for the transaxle, I replaced the oil and it seems to work great. It does act a little strange with bypass enabled. It should stop any motion of the axle but it slowly reverses when full reverse and it jerks forward but only when in full forward. I performed the purge but it didn't make much difference with the bypass issue. Since I don't see that as a big deal (I'm not going to be running the engine in bypass for any reason I can think of), I'll not worry about it.
It looks like the electric clutch is running all the time which is a more concerning issue. I'll have to look into that since I'm not sure about how the electric clutch engages.