After the M42, let’s talk about Apple’s M43… The M43ADP1,1 (Apple Development Platform) is the prototype for the Mac Pro.
There are some mentions on forums: here, with overclocked 3 GHz Xeon ES (prototypes), here with the same processors as the first Mac Pro.
There are also three references on Geekbench. In all three cases, they are equipped with two quad-core processors at 2.4 GHz (no commercially available model uses these processors).
There is relatively little information about this prototype.