What the heck is that

For a drag car with a high stall converter it would work ok. Not the greatest setup for the street getting rid of the vacuum pods that should work the outer carbs.

is that to make the out board carbs manual instead of vac operated?

Those carbs are the MP performance (or Ford) carbs. They are mechanical. No vacuum pods. They worked on everyday HP Ford offerings. Why would anyone think it needs a high stall and gear is beyond me. Though I’m sure they didn’t come with 2.76 gears....