Re: Mercarb rebuild kit
If it's a Mercarb, it's made by Mercury. Rochester stopped making the 2bbl that Merc was putting on it's motors so Mercury designed their own. You can tell it's a Merc because the Rochester had two idle mixture screws whereas the Merc has only one.
There are two different rebuild kits depending on whether you have an older or newer style Merccarb. The difference is the accelerator pump. The older pump rod is straight and is cut off flat at the top. The newer has a 90 degree bend at the top. I would think being a 98 you have the newer carburator.
Older Mercarb Kit: 3302-804845
Newer Mercarb Kit: 3302-804844
When DonS gets in here, he'll probably be able to give you more specifics from your carb casting numbers.