It does seem odd that no one make those 47-55 panel-body rear fenders.
Typically the minimum crank out on sheet metal parts is 1000 units {most factories will not even tool up for anything less than 1000 units}.
So the vendor invests a butt-load of $$$ to have 2 tools made & then he pays to have them stamped out & then he pays to have them shipped from the other side of the globe to get them here.
Now he has hundreds of thousands of dollars tied up in a pile of 2000 new fenders.
He tries to market them & all he hears is....
"They are too expensive"
"Shipping is too much"
"I only use original parts on my truck"
"These are cheapo Chinese parts"
I don't think that there are 1000 burb. & panel owners out there to buy all 2000 fenders & even if there is.... the vendor would still need to twist arms to get people to buy them.
That is why no one has reproduced them yet T.C.