Generally not on bike at all, the seat bolted down solid. If anywhere it would be under left side cover where the small toolset was, in the storage triangle box built into front of rear fender. You used the key to open it.
Part #3 there. That book was pretty thick, IIRC it may have not fit there either. I had '80 and almost identical bike. Thinking the shop simply handed me the book along with other paperwork.