Depends very much on the year. Earlier bikes were 1 and 1/8" semi integrated or integrated top and bottom, later bikes were tapered with 1 and 1/8" top and 1 and 1/2" integrated. Felt use very good quality bearings as stsndard so only a naughty boy allow them to degrade to the state that they require replacement
Look on the steerer for a S.H.I.S. number, which any bike shop with a brancell between them can use to identify what you got.
If in doubt phusically take it to an LBS.