There was a cross-posted thread in a couple of message boards; one for TSR's Buck Rogers RPG, and the other in the late TS/S.I. forum. The post stated that the Buck Rogers: XXVc was possibly going to be powered by the Top Secret/S.I. system.
In the end it didn't end up that way, The Buck Rogers game used a variant of the AD&D system, THAC0 and % skills, etc.
Here is that discussion:
--- In firstname.lastname@example.org, Justin Mohareb <justinmohareb@...> wrote:I think the game would've held up well using the d% skill based system. It wouldn't be difficult to convert. In fact TSR published some information on how to do that very thing. These articles appeared between stories in the issues of a comic-book/module series called Intruder.
> I spoke to Doug Niles at a convention a long time ago (gah I'm old) and he
> did mention that he'd lobbied to have Buck use the TS:SI rules, but was
> overruled. I'm not sure about how wide/deep the discussion was about using
> a system other than AD&D.
> On Mon, May 16, 2011 at 9:28 AM, Renin <webasaurusrex@...> wrote:
> > I could swear I read somewhere that Jeff Grubb or somebody tagged to
> > develop the Buck Rogers XXVc game had originally argued to use the TSSI
> > rules. Does anyone else remember seeing this?