They might be on a loose drive, somewhere. Hard to say. But, if any build details will help, I do remember those:

The Cougar chassis needs to have the rear wheelwells flattened, and if you are a stickler, chop the pan after the gas tank and make a filler panel with sheet plastic (I didn't, tho.) You will also mill off the locator tab under the bed.

My interior was the front 2/3 of a Countdown '66 Mustang. I cut at the edge of the door line. Then fitted with leftover seats from a stock "SSS" '65 Fairlane. IP was from the Falcon, rear wall was scrap plastic, with some fudgery for fit.

Not sure if it was the kit firewall, only that it was a decent approximation of a Ford from the era. Engine was from the '65 Revell 1/24 Mustang 2+2 FB, using the kit headers, drop fit to the chassis after tickling the mount tab on the cross member. Driveshaft was fabbed with stray U-joints from the junk box fitted to a length of aluminum tubing. Used the Cougar dual exhaust. Of course, you can use the Boss 302, or whatever else will fit in there.

Wheels and tires were the AMT L60 in back and solid blue streak F70 in front, on vintage type "Hands" mags from the Blueprinter parts pack (WAYYYYYYYYYYYYYYYYY overdue!) for a nice rubber rake.

That was pretty much it. I'd painted it in the '70s with a leftover rattle can of AMT Black lacquer, rubbed several times over the years. Touched up the burn thrus with a black sharpie, probably need to hit it again when it comes out of storage.

Just a nifty little whip, one of my favorite builds. When the new Cougar arrives, I'll knock one together in white to test the fit of the (somewhat) more accurate chassis, or my laziness will take over and just pop one of my MLRC resin Comet I-6's in there and call it good.