You may have to estimate the year by comparing serial numbers of other Bolers from the same factory. I have a 1976 built in Winnipeg,
Model # 130-A-S and Serial # 360072 .
has two stickers with different dates, one next to the door shows March 15, 1976 (maybe the date sold?) and the sticker on the service side shows Nov. 1975, probably the actual build date. I don't know how many were built each year but I'd guess that yours was 1974 or earlier. Hope that helps, maybe others with Winnipeg Bolers can help narrow it down further.