I was intrigued by the 446 in a Dodge so I went looking,don't recall hearing of such a thing.
Sure enough,it was for a very short time in Motorhome chassis. There's no way it was used in MD trucks since they were discontinued in 1977, a year before the RB big block engines ceased in Aug. 1978.
Here's a quote and a link to where I found it.
The company built a large run of 440 V8 engines to keep their motor home line going, just before discontinuing the big engines; when those ran out, around 1980, they substituted the International Harvester 446 V-8 in their Class A motor home chassis.
http://www.allpar.com/trucks/campers.htmlI found the same basic info elsewhere including Binder Planet.
IH would never have used a part like that emblazoned with another makes name,you can bet on that. Plus the MV8's in IH trucks had AC's that are about 7 inches +/- in height,with a much shorter and broader air horn.
People collect and restore all kinds of things,MH's included (though I don't know why?) so you might try a forum for that genre. Someone just may need that AC and I'm sure they're hard to find.
12 yrs.exp. in IH dealer parts dept.
Never argue with a fool...
If you don't have anything nice to say...say nothing.
If you don't learn something new everyday...you weren't paying attention.
THINK! Be sure brain is connected before mouth is in gear.