Dave Frisch said "You might want to try K&M seats. I had good luck with one of their seats about 8 years ago.

http://www.tractorseats.com/" 

Interesting you mentioned them.  I got a private email from a friend suggesting the same thing.  So I just dropped K&M a kind of pointed note (this is an excerpt, I went into more detail):

"I bought a seat back (unknown brand) at the Farm Expo in
either 2004 or 2005 from CFC Distributing.  It has failed miserably.  The metal seems to be thinner than the standard garbage can and the mounting bolts for the small cushion on  pulled clear out of the metal.

I have heard from other folks who have been equally dissatisfied with the seat backs on their '06/'56/'66 series IH tractors.   The OEM never  bent, you just wore the upholstery off of it.

A friend said he had gotten a K&M seat for his 1486 and so far was satisfied.  What I am looking for is assurance yours will do better and a reason to believe you."

Got this back from Kevin:

" Hi Mike,
You have our guarantee that our backrest will not bend. It is made right here in Renville, Minnesota - it is not an import like the CFC product. If you are dissatisfied or if it should fail (we've never had one bend) we will replace it, no questions asked.
If you have any questions, you can reach me at 800-328-1752 ext. 113.
Thanks,
Kevin. "

I may have to try them.