'87-'89 Ford Escort
rear seat Seat back width = 42"
Seat bottom width = 42"
Seat back thickness = 3.5" (seat back folds forward)

'90 Dodge Caravan,
middle seat? Seat back width = 44.5"
Seat bottom width = 44.5"
Seat back thickness = 4.5"

'80s Isuzu Trooper
Seat back width = 48"
Seat bottom width = 48"
Seat back thickness = 3.5"

'84 Ford Ranger
Seat back width = 49"
Seat bottom width = 49"
Seat back thickness = 3.5"

'84 Toyota van
middle seat Seat back width = 34"
Seat bottom width = 36"
Seat back thickness = 4.5" '91

Ford Festiva
Seat back width = 38"
Seat bottom width = 48" (odd shape is fitted to wheel wells)
Seat back thickness = 3.5"

'89 Ford Aerostar
middle seat Seat back width = 39"
Seat bottom width = 46" (odd shape)
Seat back thickness = 4.5"

'91 Chevy S10 pickup
bench seat Seat back width = 48"
Seat back width = 5.5"
Seat bottom width = 49.75"
Seat bottom thickness = 6"
The seat would bolt to a flat floor, with the frame the bottom cushon at highest point looks to be 9.5" high. Bottom cushon has two holes for seatbelts to pass through.

Wrangler stuff
(pretty small - maybe good for Model A)
Seat Back Width - 32.5"
Seat Back Height - 15.5" (from hinge)
Seat Back Thickness - 5"
Seat Bottom Width - 33.5"
Seat Bottom Thickness - 5" (at bolster)
Seat Bottom Depth - 15.5" (front to back)
Found one that mounts to the floor in a severely channeled 26-27 T

90's Isuzu Amigo back seat.
SEAT BACK 39"x21"x3"
SEAT BOTTOM 39"x20.5"x8" Seat folds forward and the "folded seat" folds forward again!

85-6 Dodge Colt Vista van
rear (3rd) seat. 38 inches wide-21 inches deep.
integral retractable belts (center) earlier ones don't have headrests thin cushions and backrests