Apple have been very cagey on the origins of the Brundlemac. All were unique, most were generally compatible with one another, but all had one or two ports that didn't seem to connect to anything else.
"...the occasional moaning and sighing is the worst part, but if the ominous error dialogs and expressions of terror at being shut down don't put you off, you'd do worse than this very well priced bundle. In some markets, Apple are paying customers to take Brundlemacs" - MacWorld, September 1997.