The NAPA dealer was able to cross over the engine oil filter to there part number. Probably could do the same with the transmission filter. NAPA filters are made by Wix and the Kubota filters are made by Fleetguard to Kubota specs.
Here is the information from the Fleetguard web site.
BX22
Air AF25745 1 FLEETGUARD
Note: FLEETGUARD AF25745 replaces OEM part KUBOTA K121182320.
Lube, Full-Flow Spin-On LF16050 1 FLEETGUARD
Note: FLEETGUARD LF16050 replaces OEM part KUBOTA 1524132099.
Fuel, In-Line FF149 1 FLEETGUARD
Note: FLEETGUARD FF149 replaces OEM part KUBOTA
1258143012.
BX2200 & BX1800
Air AF25745 1 FLEETGUARD
Note: FLEETGUARD AF25745 replaces OEM part KUBOTA K121182320.
Lube, Full-Flow Spin-On LF16050 1 FLEETGUARD
Note: FLEETGUARD LF16050 replaces OEM part KUBOTA 1524132099.
Lube, Full-Flow Spin-On LF3403 1 FLEETGUARD
Note: FLEETGUARD LF3403 replaces OEM part KUBOTA 7000015241.
Fuel, In-Line FF149 2 FLEETGUARD
Note: FLEETGUARD FF149 replaces OEM part KUBOTA 1258143012.