So the warranty won't cover a replacement? So we have to assume that you caused the damage to the lock and don't want to claim it as a warranty item?
Nevertheless, I'd think that a Fleetwood dealership's parts department that has access to a catalog of Fleetwood parts could narrow down the exact part number.
Or call Fleetwood's parts and service customer support at 800-322-8216 or click here
for their website.
They do have an online parts catalog through Allied Recreation Group. Here is their webpage and phone number/email information: Click here