Ye Olde Idler Arm Question Again

[Mark McDonald <tomswift@xxxxxxxxxxxxx>]

Okay, folks, I'm trying to help a guy get the right idler arm for his 
'73 Imperial.

I called the local NAPA store and they have one for $58 roughly which 
the man on the phone swears is for an Imperial, not a New Yorker.

The local Autozone has one for roughly $169 plus a $35 core charge.

The discrepancy in prices leads me to believe one of these is the wrong 
part, but which one?  I'm guessing the more expensive one is the right 
one (of course).

The parts section of the IMl has part #s up to 1970 but not for '73.  
Can someone tell me how I know which one is correct?  (I do not have 
the '73 part in my hand to compare it.)

Thanks, Mark