I have a topper on my convertible and like it a lot. One problem is that the standard battery hold down brackets are a bit too narrow for the toppers. Someone helped me modify the bracket to work so I was finally able to use it. I will never go back to a resto battery on this local show and cruise car!
IIRC I read recently the battery topper place isn't doing Mopar ones any more even though they are still shown on their website. In the post I saw that in, someone said they were still able to buy them at Year One though.
My T/A is a show queen so that is why I want to get a resto battery for it. I do have a DOA group 24, so the idea of gutting it and installing a small battery inside is appealing to me more every day!