Thanks so much for the reply. Also received a PM with offer of assistance. Both very much appreciated. I love the willingness of forum members to help. What a great community. I will definitely follow up.
PSA to folks who buy used cars/trucks with wheel locks...Make sure you have the adapter to take the wheel off or ifin you have a flat, you are going to pay an expensive tow bill and be inconvenienced to have the lug removed at a shop.... Seen it many times on the side of the road!!!
Hope you get the answers ya need and find the adapter...
Check the glove box and center console for it. Looks similar to a socket (from a socket set). I bought a truck and about 3 months later, I found this odd looking socket thing in the small coin box or the like, inside the center console. Check there and in the trunk, sometimes people put them in the jack bag, maybe you'll be lucky too.
Looks like caddy hub caps. I'm sure the yards have the keys. Can't hurt to call. They were very expensive back in the 80's. Think caddy made 4 or 5 designs. That was one, triangle, square I remember well.
If the key is mia, I've always had good results by tapping a flat head screwdriver into the straightest groove in the pattern and turning.
Don't use a screwdriver that you like, it will get beat up pretty good.