The have a lot of GL parts - some NOS - listed on Ebay, most up for bids, but low starting bids:
https://stores.ebay.com/onestopoutlet
I'm going to try them for mirrors, horns, and a front emblem for the '83.
https://stores.ebay.com/onestopoutlet
I'm going to try them for mirrors, horns, and a front emblem for the '83.