Getting trailer title from old tag?

[73 Dolphin]

Maybe you can help me out. I bought a boat and trailer - the boat had a title .The trailer did not. However the boat had in it an old tag ( exp 2000 ). It could have been for the trailer.

Is there a way to run the tag number free of charge to check if it was for the trailer?
I wouldn't expect to be able to do it for free with a current tag ( stalkers should have to pay! )but hopefully given the age there is a way.

Any advice would be appreciated. Thanks.