Review on 👍 Genuine GM 15908046 Rear Window Wiper Arm: Superior Quality for Optimal Performance by Jeff Wieczorek

I bought this replacement lever for my 2004 Envoy GMC SLE and it didn't fit. In a previous review someone asked if the nozzle was slotted or smooth and was told it was slotted just like mine. It had a hole that was tapered but smooth and too big. My GMC has a tapered wiper shaft about 1/2" diameter on the inner end and about 1/4" diameter on the outer end that is secured with a 7/16" nut. The wiper arm is awkward and doesn't wipe the entire rear window (I thought this was a common complaint about this year's GMC and this replacement was recommended to be repaired). To my knowledge this is the original wiper motor (I'm the second owner) and given the way this new wiper arm with the 16" wiper blade fits onto the glass and tailgate it just doesn't feel like the right part . I checked the part number and am at a loss as to what to do. Does this replacement arm need to be internally splined as stated in the comments and will it fit the size of my wiper shaft described above? Perhaps a photo of the connector (under the heading) would help me confirm before buying. The part number matches the GM numbers, but the GM parts diagram looks like a different wiper than the photo, which looks exactly as I received it. Many Thanks,