Defrost Tubes for Narrow Body

[Detroit Iron]

I've been all over the heating/AC forum and didn't quite see the info I'm looking for.

I have a '64 Barracuda and want to buy/fabricate defrost tubes. Here's what has me baffled: The measurements on the heater box for the tubes are 2" and 2 1/4". The vents up under the dash are both 2 1/2".

Is this what the rest of you have experienced???

 

[68original]

Yes.
Not only two different diameters, but the factory tubes have a larger diameter at the top to go over the vents in the dash.
Another weird feat of Mopar engineering.

 

[RedFish]

The two different diameters so drivers side got larger share of the air. Aftermarket hose kits, from DMT and others, include adapters so a common continuous diameter hose will work at all 4 ports.

 

[4spdragtop]

Heres a "how to" that a member here did
Cheap Defrost Hose Fix

 

[64conv65hard]

Here's the adapters you need.
Nostalgic AC - Duct Hose Adapters - Duct Hose & Vents