Here are the specs of the truck: 1982 F350 4x2 DRW Single Cab, 4spd manual (T18?) with a 400ci V8 (at least, that's what the valve cover tag and VIN says).

I bought this dump truck at a local auction a couple years ago to use locally. I have gotten some use out of it while also fixing it up a bit with my shade tree "skills." It is a true beater and will pretty much never be nice again, but it does what I need it to do at least 50% of the time. That said, I would like to make that percentage go up a bit. Here is my question:

The PCV tube off of the oil cap has never ever been plugged in, It just kind of dangles up into space. A previous owner replaced the air cleaner assembly (and maybe carb?) with a 351 air cleaner which is a different size than the original 400 air cleaner but didn't replace much else, and the tube doesn't fit. Since I have been driving the truck to middling success, and since it's mostly a mechanical beast, I just assumed "it doesn't really matter" and I have been driving it. I am starting to realize that maybe it does... my dumb question is: What are symptoms of driving with a disconnected and unplugged PCV valve? The thing has had major vacuum leak issues. I solved some by doing a carb rebuild and some other things but it's still there.

 

Are you sure that is the actual PCV valve? If it went to the aircleaner it is actually the PCV system air intake. If the oil cap has some steel wool type stuff in it, then you are right, it really doesn't matter. The real PCV valve should be in the other valve cover and go to a vacuum port under the carb somewhere. The PCV valve sucks on the guts of the engine, and the air comes in from that pipe hanging in the air. If you want to hook it back to the aircleaner with the little foam filter in there you can, however you can rig it.