Hubcap and mounting frame

I have a 1989 Fleetwood Bounder. I lost the rear hubcap and frame for attaching the hubcap to the rim. It is a 19.5 rim. The hubcap has a center knob with a threaded bolt that goes thru the center of the hubcap and screws into the framework that attaches to the rim. If anyone outhere knows who might have one or where I could look for one please let me know through this site. I am in Southern California, San Diego, County. Thanks