Help starting

[BBO]

I know through research the part number I am looking for is miu10638 which includes the carb gaskets.

This number may be only gaskets, and might not be the correct ones.
See if this is any help...
Onan 146-0496 Carburetor 20HP P220G P220V P248V B48M B48G LX790 Onan 146-0496 Carburetor 20HP P220G P220V P248V B48M B48G LX790 [146-0496] - $159.00 : ONANPARTS.COM, Rebuild Parts for Onan engines