Interesting manifold

Haven't seen this one before, no; I'll file it with these weirdos and this one.

Looks like the Speco item is configured for a pair of progressive 2bbl carbs, like Webers. That would explain the linkage orientation.

To me it looks like that hotbox arrangement…isn't. Unlike the Offy № 5041 twin 1-bbl intake, there doesn't appear to be any actual path for exhaust to circulate under the two plenums. The box itself appears to be closed on all four sides.