Late-1980s/early-1990s 50W head (the D-series period).
Marks that can be entered for this maker: Serial number (plate), Transformer code.
Nothing predates 1980; components only push the date later.
Sold-price aggregates are not collected yet, so the archive gives no figure — condition, originality of the transformers and a documented recap move this model more than any list price.
Evidence: Blue Book of Guitar Values — hiwatt