My car is not a convertible, nor did it have roll up rear windows (deputy model), however I did strip a 70 hardtop of it's rear window hardware to install in my car. Here's a couple pics of the part you mention installed, the brackets were both in my car, even though it did not originally use them. No idea if a convertible has the same brackets. By the way, I need one of these for the driver side, how long are the ones from Roseville?
jess