Hey Steve,
This one is tough since virtually all Japanese guitar companies of the late 1960's had their own version of the violin bass. However, turns out the Crown logo was very useful in this case. Most logos on late 60's Japanese guitars were put on by the distributors, not the producers. However, in your case, Crown was a Japanese manufacturer that produced instruments for the domestic Japanese market.
Unfortunately, I don't have a picture of your bass. However, I do have a picture of it's 12 string guitar cousin. Also note the similarity between the Minister bass at the top of the photo and your instrument. I don't know the relationship between Minister and Crown but judging from these two instruments, they were produced in the same factory. Both of these guitars are from 1968. The main difference I see between these instruments and your bass is that your bass appears to have more rounded shoulders. I still think we are fishin' in the right pond.
![Image](http://www.vintaxe.com/forum_pics/1968_crown_violinbass.jpg)