Your VIN decodes as:
1FABP - USA, Ford Passenger Car, Active Seatbelts
28 - 3-door Hatchback (L/GL/GLX/LX/GT Series)
M - V8, 5.0 Liter, 302 (EFI) Engine
7 - VIN internal check digit
G - 1986 model year
F - Dearborn Assembly Plant
325491 - Consecutive build number
There is also a tag on the door. The codes on that tag will tell you what type of transmission, axle ratios, paint color, etc. Post that information and I'll decode it for you. Or follow this link and decode it yourself (this link gives tons of useful information on the various years and the differences and so on).
http://www.mustanggt.org/forms/86decode.htm#vin