Just checking through my backups, so don''t know how many of these are still around or where:

-Zygote/DAZ had a really nice one as a freebie quite a while back (5/2000) with some great textures posted here by SpaceDuke.
(see this thread for a partial view of it in a lighting tute post)

-MorphingStage by zaara is also pretty elaborate (11/2002)

-Also see the Rock Stage by Richabri for some parts. Trusses & instruments & such.

-I've got one by Staale named "Stage", but have yet to try it and the tiny thumbnail does not provide much detail.

Staale's & Zygote's were on their respective sites, and I believe the other two were originally posted in FreeStuff here.

Though I've not used it, the one by zaara looks like your best bet for a freebie. If you can't find it IM me & I'll check the readme for an addy.