I believe Mike Mentzers Heavy Duty Journal is in The National Museum of American History in Washington, DC and is being protected by 6" bullet proof glass.
Sorry, it cannot be accessed.
Oops. Wish I'd held onto my copy, then

It was an interesting book. Intenceman could probably tell you all about it. The thing that most stood out to me was Mentzer's rest-pause training, which he used to whip himself into shape for his Universe win IIRC. He'd do about 6 max singles with 10-15 seconds rest in between. Usually someone would either help him complete the subsequent reps by providing just a little resistance, and/or sometimes he'd drop the weight a little.
As far as a bodypart split goes, all I remember is him doing a 2 on/1 off type thing. And some stuff in the book was weird; e.g., in the first workout, he'd do something like chest, back and shoulders. The next day, he might do legs, abs and arms ... but I distinctly remember that he mentioned doing a set of incline press on the leg day

Granted, he was somewhat out of shape at that point, but some of the overlap struck me as odd.
I know people who have tried his style of rest-pausing to great effect. It never helped me much ... I just seemed to overtrain. Dante's rest-pausing worked for me and that German P.I.T.T. stuff treats me kindly on occasion, but Mentzer's best stuff was in his '92
Heavy Duty book IMO.