Honestly, I don't know. Since there is no cardboard left on the orig unit, it's impossible to tell from the picture that they had. I'll probably have to look for some kind of a part number on the internals.
StudioSonic is also something that I have stumbled across while doing my searches, but never found a pic, so you one upped me there. The picture of the StudioSonic reverb unit does appear to be of the same dimensions, so that is a positive sign.
It's also kind of funny because the eBay link that you provided, I actually placed in my "Watched Items" a few days ago. But without knowing which reverb unit was installed, I have been hesitating on buying the replacement cardboard.
I'll try to provide some pics of the reverb unit in the truck and hopefully, a part number as well.