Most of those numbers are "company gobbledegook", but I suspect the L7 might be their code for seed size.
ASk that seed dealer for a Golden Harvest phone number, then ask them what it L7 means for plate info.
If they don"t know, buy from a seed dealer in your area who knows how to help you.
Some seed companies get too full of themselves and forget how to keep this info simple.
You find out the "real seed size" and I can help you with info on the exact plate you will need.
LA in WI