We bought two new 306A`s around 79- 80 they were the early type with stamped steel mufflers tat did not last very long before the rust destroyed them, the saws lasted a long time and had great cutting power in the wood we cut back then, later on I found the cast aluminum mufflers to replace the rusted out steel ones but by that time we had moved on to using Sachs Dolmar saws. I never knew that the serial numbers could be deciphered to tell the year of manufacture.