Technical Help identifying quick change lower shaft

I have a qc lower shaft , in great shape with gear marked . 12 . 5 -28T 1.43 . It's 19-5/16 overall length ( not including the bolt threaded into the end ) no idea what it is. I know the previous owner did a lot of halibrand stuff but not sure if that's what it's from. Any help is much appreciated . Thanks !