Designations
As is common at this time this weapon underwent several name changes. At various times it was known as K44, Pak 44, Kanone 81, Pak 80 & Pjk 80.
The equipment numbered in the 8x range were temporary equipment issued usually in small numbers and not regarded as standard issue service weapons. Hence Pak 80 and Pjk 80 were temporary names as were K81/x.
Had this equipment been accepted into full service it would have had a Pak 4x designation attached. The only difference between the Pak 44 and the K 44 was mode of operation—the weapon itself was identical.
There is some disagreement about the Pak 80 and Pjk 80 designations with German and English sources disagreeing which is correct.
Read more about this topic: 12.8 Cm Pak 44