This one was listed on ebay in February 2010.
I do not know yet what the "DF" code means but I can tell you that it is not for the seat color or material. It's just a coincidence that the INT. TRIM code on your VC Label (door tag) is "FD".
MUSTANG = model line
231681 = 31,681st 1986 Mustang assigned a VI at Dearborn Assembly
66B = Mustang 2-door sedan
M = 5.0L V8 engine
0100
DF
ST
SK
AC = factory air conditioner
01
S = cruise control
MBW = T-5 transmission
01 = hood w/o scoop
D = Canyon Red interior
EI = EFI
01
1
X
1
4
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