On my '51, there were clips at the bottom rear of the window run channel, and small flat head sheet metal screws along the rear and top of the window opening. The division bar got small tubular rivets to hold the channel on the front. The clips might be available, but today's glues would probably do a quicker and easier job. You just need to be sure not to use too much glue.
This video shows the window channel installation on a '52. Your truck would be similar.
