Install the glass first, then the wing window assembly.
Not real up on first gens, but if the rear run channel is bolted in, unbolt the track so you can slide the glass all the way back. also remove the lower glass stop if there is one. this will allow more room the install the wing ***.
once the glass is on the track, slide back and down as far as possible. place the wing in position, and assure the glass is in both the front and rear run channels. adjust the run channels as needed for smooth operation, and tighten everything up. piece of cake.