You can swap most any engine, you will need to see if the shaft size are the same and length of shaft are same, is the Engine a single or a twin, if it is a flat head opposed twin you might have clearance issue with the hood of tractor, also if tractor now has an electric clutch for pto and the swap Engine does not it might not charge enough to keep battery charged and run electric pto, we need more info on engines, what is the numbers off the 98 engine and what is in the Husqvarna now ?