In regards to Blower manifolds, Cragar, M/T, HM, and Weiand made them. These are Low/Medium intakes and there is the Magnesium Ford script intake for Hiriser many credit M/T for. In reality that intake shares no features of any M/T blower manifold so I'm a bit sceptical on that "eBay" theory. Mostly being it shares all if the traits of the HM low/medium riser intake including the pop off valve design. If you look the Blue Thunder is a direct copy of the HM manifold less the logo. The pop off pad is there too but it is cast solid so it can be run with various valves or a burst panel.
The reason the HM intake in the eBay ad lacks the distributor hole is because you more often than not used a distributor off set drive timing cover or ran the mag off the front of the cam. HM Cragar and M/T all offered these. While steep, for NOS he's not out of line. A BDS converted Offenhauser 2x4 is $1400 new for FE.
Anyway for anyone in need Dyers has been producing a brand new one piece blower manifold for a few years. Bill Dyer contacted me when they were preproduction in seeing one of my want ads for one. Their intake is a tunnelwedge with a blowerplate instead of carb pads but it is cast that way not modified like the BDS units. For guys interested in running a distributor this allows clearance without a blower spacer.
