My first post. Thanks to any and all who can offer some guidance here. 1988 Silverado, HVAC interior air box linkage has plastic retaining guides that have literally disintegrated, setting the tension springs free. They work with the actuator to control vents. Have tried the "typical" online website sites that begin with the letter E--y and A-n, without luck. I'm including a pic with the part circled. Not much luck in my area salvage yards. The one that had the parts wanted to sell the complete air box (300.00).

 

probably junk yard special, good luck!

 

From the picture they don't look too complicated. You can probably make something that will work. You may also find them on a different year and model that could work.