I did purchase a Precision Scale car a while back. Got it for a reasonable price. It was painted but not lettered. I took a chance that I could at some point. Get a reasonably priced decal set. It tracks the layout without derailing. So I kept it as is. Pretty close as far as body and chassis. The length appears to be spot on.
The Lionel car has the wooden body and tanks removed. Without examining another car. I’m really not sure how it was done. I’m guessing the body was carefully sawed off. Then sanded flush. Seems to track the layout well. If I ever run into a problem. It’s good to know. I can convert the trucks back and simply shim the Kadee’s.