A few other things I am having trouble finding:
Urethane front bumper (perhaps impossible to find)
Grill center support bracket (single center bracket version)
Rear seat foam kit
Front seat base (lower frame and seat spring assembly)
Thanks,
Gene K.
Try the usual suspects first, Ebay, Don at Ohiomustang, 71steed on VMF (coram Corral on ebay) Hemikiller on here or VMF and see if they have anything.
The reproduction rear interior quarter panels are garbage i bought a set they would only be good if your desperate or have a track car and needed a very light interior. those panels need to be cut out for everything. you need to cut out holes for the belts and the ashtray.
you have a late 72 car because you have retractable rear belts similar to the 73 cars. so you would focus on 1973 cars to get the correct rear panels.
73s are more numerous, 72 is the rarest year of mustang.
Original quarter panels that are unmolested and not disintegrating are rare and will cost you over 400$ in today's market. It took me 2 years to find a pair in good shape from Don at Ohiomustang.
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Urethane front bumper: another rare part to find in good usable condition.
these pop up on Ebay from time to time, they go from 200-1000$ depending on condition took me 3 years to find one in excellent shape. the Urethane bumper was only put on some models from 71-72, in 73 the bumper was completely changed. so you have less then 200,000 vehicles that may have one, and 40 years of them disappearing from existence.
Its not impossible to find one but will cost you lots of money. i ran a chrome front bumper for about a year before i replaced it with a urethane one.
rarer then the urethane front bumper is the Crash bar Re-enforcement plate that the bumper mounts on to, this part is usually rusted away I found a NOS plate for about 200$ on e-bay. also took me 3 years to find. the chrome and urethane bumpers on the 71-72 is the same, you can easily swap in either bumper onto your car.
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Grill center support, hood latch support, single center version, should be easy to find, common to late 71,all 72, and i think 73 also not 100% sure.
its 2 pieces, the main part that holds the hood latch is attached to the radiator support, and there is a smaller adjustable plate with 2 bolts that attaches to the grill. I think i got one from Coram Corral (71steed)
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rear seat foam(aftermarket) this does not exist.
you either have to salvage your original seat foam or make your own. I recommend going to a fabric store or a furniture store , use your original foam as a guide.
i ended up throwing my foam in the washer on low once all the dirt and garbage washed out of the foam i left it to dry on a rack, and it puffed back up. all the other original parts to the seat, like the re-enforced burlap and musklin fabric under covers must be fabricated yourself. the front seats are easier to rebuild with the aftermarket, because most rear seats are in good shape and were never used.
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front seat base, should be easy to find they always need to be repaired they are usually cracked with broken springs.
i Brazed my seat base back together and used Sofa U springs from a furniture store that matched the original ford springs, i then replaced the broken originals with new and re-assembled.
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None of the things you want are impossible to find but will take time and patients and money.