[Burbnasty]

In our convertible Buick, we never lock it. That is the advice I've always been given, if they want to get in they will just cut the top and cause more damage as stated above.
Also anyone who actually knows what the retro sound is, is probably someone who also knows old cars and trucks.
I like to think that old car and truck people are respectful enough to not steal from each other.
So probably between the OG looking stereo and unlocked door people will just move on.
Best of luck.