My 1978 Alaskan (serial # 1276) was built in Manheim, PA and the quality of workmanship was unexpected - bookmatched door fronts and all. Manheim, PA is in the heart of Amish country.
The windows and teardrop marker lights on the sides are period correct to a 1960's Alaskan, so nobody would be the wiser if you called it a 1962 or a 1965. It would help to know when they started production at the different locations. My guess is that the serial numbers were sequential.
Have you bought it yet?