Clarification on '69 Camaro L89 head design

[LS6 RAT]

427king,

That's what I'm confused about. Every L-71/L89 Corvette optioned engine uses the closed chambered '842 head, all have the threaded plug. This head of course is also used on the majority of the 116 '69 L-88 Corvettes. I believe the last 44 L-88's were equipped with the 2nd design head, which of course is the '074 developed for the ZL-1 and used on all of the 188 1971 LS6's, this head of course did not have the plugs.
In an article written by Roger Gibson on aluminum heads, published in the Corvette Restorer magazine a few years ago, it shows the different aluminum heads used on Corvettes from '67 thru '71. Never was any mention of the '842 head manufactured without the threaded plugs. I'm just wanting to get educated on this.