Ian,
The whole thing is like some silly comedy routine.
I guess the first thing is to make sure we have the same wiper assembly! I am sure this is the case, but considering the distance between us that is probably a good place to start. I am working with '66 GP & Bonnevilles. I have got a half dozen assemblies and all are the same.
If you have a set of refills that you can take a picture of the clip end of that would be great. As best I can tell, these are an 8mm equivalent. The length does not appear to be as critical. I think I have used 17 1/2 and 18" blades and maybe even 17" at one point.
The only real issue is the outboard attachment point/fastener. It has to be able to sustain bumping on the molding or the pressure of the arm stopping/changing direction when fully extended in the cycle.
Maybe just a part number would get us all headed in the right direction over here. I checked the NAPA # referenced in the thread, and it is the whole arm assembly not the refill.
More important than all this... How are you recovering my friend?
My e-mail is 63
Safari@gmail.com
Merry Christmas!
Bruce