[Matt Monson]

That second "mystery" box is from a 924 turbo. We call it the "snail" box. It shares a number of 915 components. It's a relatively rare box because they just didn't make that many of the turbo cars. Certain of the parts that are specific to that gearbox are very expensive to acquire. If you throw it on Ebay you'll get at least a few hundred dollars for it, probably from someone who owns or races 924t's who needs rebuild parts.