Marshall Valvestate Mk.I Series?

[ibanezjunkie]

i just bought one of the marshall 8100 (100w head and matching 4x12). i checked the serial number with a guy from marshall amplification that i know who works at the bletchley joint and he told me that its from the early 90s but couldnt tell me anymore (for some reason). i wonder if one of you guys could help me put a more accurate date on it?

Head Serial no.: Z31052
Cab Serial no. 7999

cheers

[ragnarpk]

91-92 for the head