Where can the Serial no. be located on a vintage (c. late '70s) Pioneer integrated amp?

Thank you in advance for any suggestions on where to look for the SN.

aforanalog11-13-2019 8:59pm

stereo5 Details Discussions Posts This discussion Message User 6,264 posts 11-14-2019 at 12:29am Copy Comment URL Report Comment Edit Delete Usually on the back of the unit. I have seen some on the bottom as well.