I was told a few years back that Triumph had to make a decision when the order of decals for the Daytonas and Speed Triples showed up with "T595" on them. Apparently it was somebody in purchasing that screwed up, and re-ordering was not desireable because of production schedules and the added cost.
So, the original nomenclature of "T955" was abandoned, and they went with the flawed decals.
If the price is right, the '98 Daytona is a fast, funky bike. Shouldn't cost TOO much to fix, and you'll not be seeing someone else on one very often.