STEBRT3 - was a pic I put up from my manual, and prolly deleted it now!! according to the task force manual there's 2 types, the "velocity type" which is an adjustable unit that goes btween carb and manifold and limits engine speed by limiting intake flow velocity - it was standard on school buses and optional on any other 6cyl, maybe what you've got
2nd type is "vacuum spinner type" was on all 5000 - 10000 series w/ V8, and it is 'mechanically driven vacuum actuated mechanism' that limits engine RPM to 4000 max under full load conditions - this type has a throttle-body unit and a distributer unit which are connected by tubing - when dist is at certain speed it allows vacuum actuation of a butterfly below carb - type that was on the 58 283 I got awhile back
I can scan and send ya the man pgs if ya want - myself, I'd remove it all, unless ya don't trust yerself to avoid street racin w/ a full load!!
Bill
