Per the suggestion of coolhand, I just tracked down Tim LaFrance to see if he had anything set aside. Spoke with him minutes ago, he's still sharp and involved in the machine gun biz. He checked his records and the last one registered was # 138. Tim LaFrance says, "There may be a few more but they would have been post sample by that time." He said these packs were all manufactured for the movie industry (sold to two different companies that he named) as they wanted these to switch around with different guns. From the LaFrance pack owners I've spoken to, the highest confirmed pack # is 100, and that owner says he knows someone with # 101. He doesn't have any packs left or any finished machine guns for that matter, as he sold off everything years ago.
He mentioned a SRC MP5 3-lug silencer that he recently finished a batch of. I requested material on them by mail (he doesn't do email). He said they were suited for 25k rounds, $600 each, and would be the quietest you've heard.