Here are a couple:
http://www.classicparts.com/1989-93-...tinfo/61-2926/
http://www.lmctruck.com/icatalog/cd/full.aspx?Page=71
The first is listed for $79.95. I doubt the quality of LMC's is any better, but they want $129.95 for theirs. And I looked on
http://www.car-part.com (search 1990/Chevy Truck 1500 series/Grille, then "Composite Headlamps, Painted") to see if there were any in a junkyard near Leesburg, NJ, but it looks like the closest one would be Philadelphia. That's a long way to go for one that might be in poor condition when you get there. Hope this helps!!