My 2016 Keystone Bullet 251RBS has the FIC door locks that are so hard to find. I found two on Ebay that where white that took the same key for the deadbolt and the door lock. I took the tumblers out of the white ones and put them in the black door locks. I also tried to make a regular RV door lock fit but the cutout is to big for a standard lock. I was going to paint the white locks at first. I don't know if this is the same problem you are having. Keystone put the door handles that where made overseas in the Keystone Bullets for a few years. Mine looks like the picture but they are black. I have two doors on my travel trailer. They still sell them on Etrailer.com
Do you still have the original lock assembly? If so, you can get the measurements and info off of it and find the right replacement. RVLocksAndMore.com, Amazon, Ebay, eTrailer, etc. all have multiple brands and styles (yes, even FIC). The lock pictured in the previous post is a Global Link which you already know isn't a direct fit for your application.
My doors have Cutouts 4.45”x3.4” or 4-3/8 x 3- 5/16 inches. There a website that I found them on it's called Wesco Fastec. They don't carry them any longer. It was cheaper to buy the two lock sets on Ebay than buy the keys to fit my doors. One key was $28.00. I bought both lock sets for $32 and I have 4 keys. I'm still trying to find a door lock that fits the cut out in my doors that have a remote locking system or a keypad.
