Mine finally came apart where it was cracked about 15 years ago.
I don't think the replacements are available any more (there was a time that Remington would send you a new black one if you sent the pieces of the old one back).
I do believe you are correct about the stocks, but call Remington anyway to find out. The stocks were injection molded out of nylon and cannot be repaired by using adhesives or heat guns.
Wish someone would offer after market stocks, laminated is nice. I, too have a 12 with broken stock. There was one (66) at the gunshow this past weekend, an Apache Black with chromed barrel and cover for $600.
I got mine from these folks years ago http://leesgunparts.com/ you will have to call them.
they may not have the remington stock but might have the CBC
stock. CBC is I think a Brazilian outfit that bought the Remington machinery for the Nylon series. The originals had a sticker on them that tauted a "lifetime warranty"
