After I bought my first 4s15 watch movement in 2002, I started a quest to get examples of all the 4s series watches that Seiko makes. Here are some photos of the 4s12 automatic. I think this watch was part of the SUS line, and came in bright red, bright blue, and black dial versions. There are a small number of other 4s12 watches made in the mid 1990's, but I didn't like their case/bracelet designs enough to buy one. Here are the photos of my SCFF005, SCFF006, and SCFF007 watches. Cheers, John.
p.s. I don't know if this really qualifies as a GMT watch since you don't set the GMT hand in this watch, you simply use the second crown to move the internal bezel to adjust for different time zones.