I got a 292 from a '67 3/4 ton stepside (ex Forest Service) and rebuilt it in '77. It had one lifter cover that had a capped off 1/2" tap above the #5 bolt hole. Santucci mentions modified sidecovers for external drainback and pan ventilation, but he's talking drag racer mods-- I think you have a heavy duty truck application that had an oil bath air cleaner. Very obsolete.
BTW, I'm using the modified /capped side cover at the rear. Can't hurt and it's different. And I'm too cheap to buy a new untapped sidecover.


Every 25 years I like to rebuild that 292 just for GP