Hello. The K200-B4 is a guitar amp (with the tremolo, vibrato, selective boost, and harmonic clipper), but if you have the effects turned off (or on if you're dangerous haha) you can use it for bass, it only depends on what kind of speakers are in the cabinet (and Kusotm offered a rather wide selection). I'll assume since it is a guitar head, it's also a guitar cabinet. Look through the literature section of the website and you should find your amp somewhere. Kustom made a few different cabs with three speakers, there were 3x15", either with three regular speakers or two speakers and a huge police siren, or a 3x12". I believe there was a post from a long time ago where someone had put up a serial number chart, if you do a search, you may find it, otherwise someone else on the forum may know. It most likely is from between 1967 and 1970 or so however. Good luck and welcome to the forum!