Try this site:
http://www.lmctruck.com
If you want new parts, they should have just about anything you need. You could almost build a truck from their catalog. I dont know if an 86 would be classified as a classic or not. In some states though, 20 years old qualifies you for an antique/classic tag. Some vehicles of that era were more collectible than others. It sometimes depended on the equip/options it had, if it was the last carbed or high perf model, if it was the last year before a major body style change ...ect....Good luck.
Later
Ed