Sepco solar water heater age

Hello Ladies and Gentleman, sorry to bother you folks But I have been all over the internet and it is to late to contact the Vaughn Corp (I think). I am trying to determine the age of a Sepco Solar water heater, I believe there are enough problems it will need to be replaced but I am just trying to determine it’s age. I hope I got the picture right. Serial# 108451514 and Model# S120SNR2, I think 10th week of 1984 but can not find it for sure.Any help would be appreciated.