Replacing a fan blower motor on a Pete?

On this '88 Pete 377, my son said the fan blower motor was squawking quite a bit, so I thought I would just replace it.(I never tried it for myself to hear the noise). Ordered a motor at local NAPA store, and started to do the install. Not too big of job, it seemed, remove the glovebox, remove one nut on the motor housing, disconnect 2 wires, and the whole thing comes out. I had to loosen a set screw, then the squirrel cage fan come off the motor shaft. Between the fan cage and motor there was a metal "flange"(for lack of a better name)..This "flange is held to the motor with two nuts, and this is what is used in the truck to hold the whole fan assembly into the ductwork.

Anyway, replaced motor, metal flange, and fan cage. Installed back in truck, connected wires and tried it out. Nothing happened first time. I thought I could have pushed the fan cage down too tightly against the flange, so I dissassembled, moved the fan cage out, and reinstalled. Worked this time, but squawked, it was dragging. To make a long story short, the fan works fine when I hold it in my hand, but when I install it, it is hitting bad. Fan cage spins pretty freely in my hand, and looks fairly level. Any ideas? I'm thinking that the piece I call the "flange" is pretty thin metal, and it could be flexing or is bent slightly out of posisiton, and that lets the fan cage hit. When I have it installed, I can push/pull the top of the motor slightly, and it will decrease the noise, but never eliminate it.

I think I have to options. Try and find a smaller diameter squirrel cage fan, and try that, or go to Peterbilt and order a new "flange" and possibly squirrel cage fan.

What do you guys think? I get so dang mad, when a simple repair like this turns into an afternoon of frustration, with no good results.
coadman