Ahhh, thanks for the tip. So therefore the 289 FIA must be CSX2259 which is owned by Lynn Park.
As for the 289 USRRC car, I can't figure out if it's CSX2431 or CSX2494. I had assumed it to be Larry Miller's CSX2488, but I'd be surprised if he'd had the fullsize windshield replaced with a small racing screen on such a valuable and original car.
You might have noticed
that I've started a thread on the Shelby Showcase cars and will update it as I find out more.