I thought the binary ones were post-1991 production. I know we found a bunch of empty binary warheads that were produced after 1991.
"The round was an old "binary-type" shell in which two chemicals held in separate sections are mixed after firing to produce sarin, Kimmitt said. He said he believed that insurgents who rigged the artillery shell as a bomb didn't know it contained the nerve agent, and that the dispersal of the nerve agent from such a rigged device was very limited. The shell had no markings. It appears the binary sarin agents didn't mix, which is why there weren't serious injuries from the initial explosion, a U.S. official told Fox News."