For one car, I used a top cover I bought off Ebay (a YearOne part, I think).
I measured a few 24 batteries and a Duralast from AutoZone was a perfect fit.
Sides of the battery are plain & flat, and I removed the adhesive label.
The top cover is wider than stock wire battery holder, so that needs to be tweaked and the cover narrowed in 2 spots with a round file.
It won't fool the knowledgeable, but everyone else thinks it's a legit piece.