To answer your original question as to what the red cap is and where it's from: It is a generic tube end protective cap manufactured by Cap Plug (brand). Cap Plug (brand) makes a large variety of plugs/caps, in a variety of colors/sizes/types, for almost any application that you can think of.
To remove it, I would use a heat gun to heat/soften the cap and then use a pair of pliers gripped on the flange at the top. I'm almost sure that the person that installed the cap heated it in a similar fashion to push it over the barb of the air cleaner nipple as this type of cap is very stiff and will not flex enough to go over the barb by just applying pressure.
The guys are correct: You need the proper breather cap and hose/clamps to complete what should have been.
To remove it, I would use a heat gun to heat/soften the cap and then use a pair of pliers gripped on the flange at the top. I'm almost sure that the person that installed the cap heated it in a similar fashion to push it over the barb of the air cleaner nipple as this type of cap is very stiff and will not flex enough to go over the barb by just applying pressure.
The guys are correct: You need the proper breather cap and hose/clamps to complete what should have been.
?). You can still opt for the Ford-style umbrella seal if you choose. The machined guide will not alter the effectiveness of the umbrella seal if you go that direction.