Honestly no idea what it looks like, I’ve just read a few threads on it.
I don’t believe my truck ever had one but at some point in its life it gained a replacement 360 that I have to assume came out of something that did. Vac advance is hooked directly to that port.
I expect some bounce in it but it was dramatic, now it’s back to only wavering a degree or so. Definite improvement.
My advance is not hooked to direct manifold vacuum, it’s on the “OSAC” port which according to other threads is where it should be. I can confirm if my carb has other ported sources but I don’t believe it does.
I have a cheap vacuum gauge on hand. I will try hooking it to the ports on the carb and see if any are ported or if the “OSAC” port is my best option.