Key pieces to the puzzle:
- Eighth digit of the VIN is "7" (86/87) or a "9" (84/85) which insures that it is an original turbo car
- RPO sticker on the inside of the trunk lid (or label in the glovebox) has "WE2" as one of the options (that's the Grand National Package)
- Look for MX0 and LC2 (trans and engine option codes for turbo motor and 200-4R)
- Ensure ALL the VIN numbers match (cowl, trunk, door, etc.)
- Look for correct badges and trim (black and grey door panels and seats unique to the GN, no "SFI 3.8 Turbo" badges on the trunk ... only Grand National badges, no red "T" badges, etc.)
Take a look here for option code (RPO) decoding:
http://www.gnttype.org/numbers/rpo.html
In 1986/87 most options were either available "ala carte" or mixed in with "Prestige Package" option bundles. It is possible for the car to have crank windows, manual locks, manual seats, and NO positraction (G80 RPO is posi), depending on how it was ordered. A WE2 (GN) will, as part of the WE2 package, have :
C60 AIR CONDITIONING
D35 SPORT MIRROR DRIVER-REMOTE, PASS-MANUAL
D55 FULL LENGTH CONSOLE
LC2 3.8 L SFI TURBO WITH INTERCOOLER
U63 RADIO - AM - MONAURAL
MXO 2OO-4R AUTO TRANS
QYZ TIRE -- BLACKWALL P215/65R15
B19 STEERING WHEEL HORN CAP EMBLEM
BY4 I/P NAMEPLATE APPLIQUE "GRAND NATIONAL"
W11 T TYPE PACKAGE
GM19 BLACK EXTERIOR COLOR
T43 REAR SPOILER
BX1 EXTERIOR ORNAMENTATION FRT END SPL
VH6 BAR -- RR IMPACT (BLACK)
The optional white letter tires QYH can be substituted for QYZ and any of the various radio/sound systems substituted for U63
Take a look here for VIN decoding:
http://www.gnttype.org/general/vin.html