Amy & Jack,
Jack: My parts manual doesn't cover the "G" model, but I will bet that the strap is the same as later models. Can someone in the club confirm? See my note to Amy below.
Amy: This strap is called a Handle Assy - Assist in the Cessna Parts Manual and is listed as P/N S1685-3. The part has been superceded by P/N SK150-72, so that is what you would order from Yingling Aviation. These buggers run about $35 new - a real bargain compared to a window latch.

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I can tell you both from experience that tracking down a good used one can be very difficult. I believe they are common with C172's, so they tend to get snatched up quickly. I see them regularly listed on the Texas Air Salvage site (Search for S1685-3), but I was never able to find one in stock.
I finally gave up looking for used and ordered a new one at a rediculous price once shipping kicked in.......only to find out that the new one (SK150-72) is NOT a direct replacement. It requires that my A&P rivet on a new bracket to use.

Besides the extra cost of installing, I would have ended up with two different door pull mounting methods, so I fabricated a temporary strap until I determine what I will do.
Dale