1964 R Deluxe Seat

I've got Serial Number 39804 and i am having the hardest time locating a replacement seat.  I have the deluxe seat from page 90-8 of the Parts Catalog.  I have the seat frame (AT16815) but i need the cushions:
1 - Seat back R34267
2 - Armrest AT168116
3 - Cushion AT16817

The parts catalog lists AR26934 as the new assembly including all three cushions, but that has been sub'd several times first to TY24856 and now finally to TY26545.  I have ordered a TY26545 equivalent eBay and Tractor Supply Company.  Neither of them fit.  So i went to the closest Deere Dealership, and they pulled the genuine Deere brand TY26545 and that seat cushion is identical to the others from eBay and Tractor supply, so it doesn't fit either.  All three cushions are the correct shape, and almost fit, but the bolt holes are significantly different and they are clearly not an identical replacement for the pieces i do have on hand.  I can probably recover the armrest, but the cusion backing metal is completely rusted out and turns to dust every time i touch it.  The small cushion in each set will fit the seat frame, but that's just a lucky coincidence i think.  So i'm stuck and don't understand why my seat frame doesn't fit those new part numbers.  Has any one else experienced this problem? I'm to the point now of getting a local metal worker to modify my seat to fit the correct TY26545, so that if it ever needs a seat in the future, there is one readily available to fit.  Before i allow him to cut on the original seat frame, i just want to be sure that there isn't some solution that i haven't tried.  Thank you in advance for any help.