It was rarely used and very expensive. Growth hormone was used first from the pituitary gland of human cadavers. This was during the height of the aids scare so most bodybuilders wouldn't use it. This was early 80's maybe late 70's. The monkey derived one was also something bodybuilders talked about but no one knew anyone that used it prior to 1980's. No, I will bet Arnold, Franco, Zane, Mentzer, Robby, Padilla and the rest never used growth hormone or insulin. Their bodies are the smoking gun proof of that.
I know it was rarely used and expensive but it WAS around and a few experimented. Arnold used cadaver GH for a little while to experiment until he got put off by the stories. I forget my source but I think he said he tried it a few times or gh15 said it (if gh15 said it it must be true
). It was definitely not used enough to make any significant impact on the physique of any bodybuilder back then because it would be obvious as day.