They were tan colored amps. A variation on Europe? This version was chrome, still with white silkscreening and serial number stamped into the right side. Caution is needed for dating amps from,and Just re-read your post.
Posted October 3,
How to Date Ampeg Amplifiers
How to Date a Fender Bassman Amplifier. A Mercury with serial number could be from September or it could be from the second serial number system implemented in In Ampeg manufactured three different types of removable back panels for the SVT. Of course, these codes are only applicable to original components, not replacement parts. The guy says it's from ; I doubt this.