I have a Mountain guitar that is a Model 400, the serial number is 19770319. It has the three piece back and solid top. The Mountain logo on the headstock runs up and down between the tuning pegs. It sounds very good and plays great. It has a very loud and clear voice and a very true neck. I'd never get rid it, it is a great guitar. Model numbers are located inside the body right under the top at the end of the neck, serial numbers lower inside at the base of the neck. A flashlight will help you find them.