oem heater box configuration 1990 crewcab

[pholliday1]

what part/foam/ plastic fills the gap between the heater distibution box and the plenum that goes to the defrost outlet in the dash for the winshield. my two pieces have a 3/4 inch gap where they come together appears to be missing a part

[ehjorten]

Unfortunately that is how they all are!  Some have a larger gap than others.  They rely on alignment and velocity.  Most of it makes it up the duct! LOL

[thirsty]

When I assembled the interior in my truck I had a good size gap also. I couldn't adjust the duct work enough to leave it and didn't remember such a big gap with my other cab. My solution was to wrap it. I had some heavy duty foil tape in the garage. I think it was muffler repair tape, pretty thick and sticky also. I just wrapped the connection of the two pieces with it. Worked out great for me.

[Captkaos]

Like Erik said, they came that way.  If you want to seal it up, I suggest Thirstys method.  I think this is just 81-87's and I don't remember my early trucks like this, but I could be imagining it.  They aren't here for me to look.

[pholliday1]

gained access to junk yard surveyed several "gutted" interiors and just like everyone has stated its comes from gm with a big ole gap and that gap on the back side is so big its like "wow that can't be right?" Thirsty is defiantly on the right track with his suggestion.

[thirsty]

One thing I noticed because I had parts from a few trucks was that they all had quite a layer of filth on the ducts. I had cleaned mine before I installed it in the cab making it easy for me to add the tape securely. There isn't much room at all between those ducts and the fire wall. I would say go the extra mile and remove the bezel and dash then the defroster duct and clean it up good so whatever you use adheres to the ducts. It's frustrating enough working in that location and you don't need to try it 3-4 times trying to get the tape to stick in place on the back side.

Just my additional $.02 on the tape trick.

[pholliday1]

Your right the interiors and ducts do get nasty. The whole reason i'm at this point is because i had to replace my heater core, and i'm in the middle of a stereo layout  and installing floor vinyl basically just finishing the interior. I have good acess to fix this problem now.