I think your best bet now is to start checking the JY for some.
There were 3 coupes in the 3 local PNP the past month 1/2. 84CD, 78CE & 78CD. most likely gone now
Don`t know if the coupes are like the sedans, if the seat bottom spring box will fit on the drivers side.
Usually the Pass seat doesn`t get the use that the drivers does.
I replaced my drivers bottom on my 85 300D form a pass side from PNP. just look for a firm one. wasn`t hard to find and about $15.00.
Charlie
There is a 50% sale coming up at PNP Sept 4TH weekend