Those are NASCAR intakes for the D3 head on a 9.00 deck block. The date on the one gives you an idea on the timeline, 07-08ish, I think on the C58 the date is under the plenum. On the other one I had that I can't remember the exact number at this time, it was designed for all aluminum 400" dirt late model engines. They do look good as far as an intake runner and plenum, for high RPM power, and show some evolution of the single 4 spider, shorter and straighter outside runners, taller plenum, etc.I bought those as possibles for my HR adapter, but decided not to use them as the Pontiac manifold fit way better for me, at least on the HR adapter, but probably would not work without more mods on a MR adapter.
Those intakes are small as cast for the interior of the ports, thick and heavy, and designed for CNC porting, even on 358" & 400" engines. It will take a TON of work to get them sized correctly for an FE stroker, not to mention the ports don't line up very well at all, especially on #1 and #8. I figured I would have to cut into at least 4 pieces, and then a bunch of welding to make it a real good intake (plus the porting). That is not to say it won't work without any cutting and welding, I just prefer a little better port alignment on all 8 cylinders, not just 2 or 4 "ish"...