Well, no luck with either place mentioned. I called Whisler Chevrolet and the guy kinda chuckled and said they don't handle old parts anymore. The other, Friesen Chevrolet, I left voicemail with parts and haven't heard back. I found one on Flea bay for $1.96 with $15 shipping frown I have tried to contacted the seller through Flea bay and the dealership to see if we could somehow reduce shipping but no reply. I even said I'd take a differential carrier gasket for my H052 but still silence. If I remember correctly the washer was listed for something like $24. I'm about ready to get some cork and make my own.
My brother in law has a tranny shop in southern Maine and he hasn't been able to find anything either. I can get the diff gasket at Rock Auto but they don't carry the packing.