Here is something that I found in another forum. I guess it refers to "production" GM motors only. Don't take this as Gospel of course, but FWIW:
"A total of only ninety (90) ZL1 engines were built: fifty-four (54) in the COPO 9560 manual transmission configuration, thirty-four (34) in the COPO 9560 automatic transmission configuration, one (1) in the COPO 9567 manual transmission configuration, and one (1) in the COPO 9567 automatic transmission configuration for the other prototype Camaro.
"Of those ninety engines, sixty-nine (69) were put in COPO 9560 cars (47 manual, 22 automatic), two (2) were put in 1969 Corvettes, and two (2) were put in the COPO 9567 cars, leaving seventeen (17) crate engines (5 manual, 12 automatic)."
http://www.camaros.net/forum/ultimat...38.html#000000