I been trying to find it on the net but no luck. GK does not have any of it's old stuff archived and I don't recall what it was even though as you see I used to own one.
I can't remember where I got it but I got it used around 1989 or 1990 and it was a 150 Watt GK bass head that predates the 400 and 800rbs.
These two photos are the only photos I have of it sorry I don't have anything better. Anyone ever seen one or still own one or have any way to get more info on it? I used to in stereo with a more powerful amp to get my highs to come out and it worked pretty well but it was under powered for the two 4x10 caps I ran it in. IN the first pic it's the one on the right and in the second pic it's the one on top the Peavy MarkIII