Bucksport

New to this forum. Purchased a 1990 Silverado recently. Had some problems with heater. It would not send out any air from any of the vents. Discovered that the person who had the truck before the guy I bought it from had installed an after market stereo. In the process he must have disconnected and lost part of the linkage to my defrost flap. The actuator motor was not aligned with the spindle properly at first. I fixed that problem. I have air to the floor and vents, but discovered that the linkage is missing for the defrost. I have searched online all over, and have found none to buy. Anyone have a source, or have one I can buy from a parts bin? Any help is appreciated.
Below is a pic of what I need. Everything within the red circle.