Before my PC crashed I had my VIN decoded courtesy of Buford 26 (thank you) under the name Stray Buick.

My question is how do I know if it is a real GS CA? Wouldn't it be easy to fake them? What can I look for to determine if it's real?

06C = body build date = June 1968, third week
ST = body style
68 = 1968
43327 = Special Deluxe 2-door thin pillar coupe (all California GS cars are 43327 body style)
BF = body built at Fisher body plant in Fremont, CA
03307 = body sequence number
TR = trim
103 = Champagne Cloth and Vinyl
Paint = T = solid color, Desert Beige
Top = 7 = Buckskin vinyl top

Option codes:
B80 = Roof drip scalp moulding
B90 = Window frame scalp moulding

Batch codes:
021984 110601
Fremont used batch codes to group options, there isn't anyway to decode these.

The VIN for your car should be of the format: 433278ZXXXXXX

43327 = Special Deluxe 2-door thin pillar coupe
8 = 1968
Z = Fremont, CA
XXXXXX = car sequence number, starting at 100,001 for cars with V8 engines at each plant