Holiday,
No... K98-K stocks won't fit a Yugo M48 or 48-A. K98's are the standard "long" Mauser action. The Yugo 48 action is the "intermediate" length Mauser action.
Just recently Federal Arms Corp. started advertising aftermarket wood sporter stocks for the M-48. I've heard of no company offering synthetics to fit the M-48.
Swampy