Here is a thread discussing the tag numbers.
https://www.yenko.net/ubbthreads/ubbt...2&page=all
In the thread Lynn posted this information which was right on for my '69 Camaro M20.
3950356 is for RPO M20 with L48, L34, L35, LM1
3946797 is for RPO M20 with Z28 & L78
3946798 is for RPO M21 with Z28 and L78
3950318 is for RPO m22 with Z28 and L78
Clint