Wow.... I wonder what the story is on these? There is a build sheet under the PS seat and it looks like they were made for an early 83 according to the VIN.
http://www.ebay.com/itm/NOS-OEM-Ford-1982-1983-1984-Thunderbird-Red-Front-Seats-Pair-T-Bird-Seat-Covers-/401157383912?hash=item5d66d7e6e8:g:BnIAAOSwZVlXj~qV&vxp=mtr
I'd say that they have been installed looking at them. Otherwise I don't see why they would have a power and manual seat track plus a build sheet and mounting marks.
Maybe a substitution for different seats or a custom order?
I agree, looks like they were installed. Who knows, maybe they have some kind of blemish we can't see but the original owner wanted new seats? If you love red, here's your chance!
Here the buildsheet decode courtesy of Foxchassis
Very early car and a 'Test' vehicle. Interesting....
1FA = Ford vehicle manufactured in USA
B = active belts, no airbags
P = passenger car
46 = Thunderbird 2-dr sedan
3 = 3.8L V6 engine
0 = VIN check digit
D = 1983 model year
H = Lorain Assembly
100058 = 58th 1983 Ford scheduled for production at Lorain Assembly
0051 = trim & chassis assembly line rotations #0051
S = Thunderbird model line
63D = Thunderbird 2-door sedan
9D = Polar White exterior paint color
DD = cloth & vinyl seating, low-back bucket (1st D), Dark Red interior trim color (2nd D)
T = test vehicle order type
3 = 3.8L V6 engine
T = AOD transmission
A = automatic air conditioner
DJ520BA = 1983 model year (D), 49-state Thermactor emissions (J), 3.8L engine (520), calibration level B, revision level A
E3SP BA = auto trans (P) originally engineered for 1983 (E3) Thunderbird (S), release level BA
S = power seat
2 = low-back front buckets
D = Dark Red seat belts
W = interval windshield wipers
E = electric rear defroster
R = AM/FM stereo radio w/ cassette
X = premium sound system
V = light group
T = tinted glass
DA = regular duty battery
V462A = Van puppies axle plant (V), 28-spline 3.08 non-locking differential (462A)
19575R4 = P195/75R14 tires
W = white sidewalls
S = speed (cruise) control