The kraton handled Bucks came out in 1988 and stated in that years catalog as, 'now available'. They are offered all the way thru to the 1994 catalog.
In that catalog only two models are shown with karton handles. The Woodsman 619 and Skinner 603, the only one that did not receive a different name. Thus,
it looks like Buck is phasing them out. So, it would depend on the year stamped on your model as to what steel you have. I know photos are a pain but it would help if you could post one showing it's stamp. DM