last year K was made was 76 starting with serial number 21801 and up from there according to a posting some time ago. The first K 1969 sn 1001. They made 20000+ K combines vs. 3000+ K2 combines. K2 started in 1977 and ran through 80 or 81..I am not sure. The original owner of my K2 claims it is the last of the 81 models made. There are F3,M3,l3........no K3, not sure why.