'''96 Litespeed Catalyst, '05 Litespeed Firenze, '06 Litespeed Tuscany, '12 Surly Pacer, All are 3x8,9 or 10. It is hilly around here!
You will have to remove the current bearings. They may either come out easily or have to be driven out of their seats after the axle is removed. A brass or plastic punch inserted from the opposite side of the hub can be used if you don't have the correct puller.
In either case there should be engraved numbers on the race or seals that will let any bearing supply house match them. Bike Tools Etc. lists numerous sealed bearings for bicycle use and may have them too.
When you install the replacements, be sure to press or drive them in by pressing on the OUTER race only. This is important. If you apply any significant force to the inner race, you will ruin the bearings. You can use a socket of matching diameter or a thick washer to seat the bearings.
It sounds like the Mallard is sealed. I hear that you can put penetrating oil in the bearings to salvage old sealed bearing hubs. Does anyone know if this is OK. what do you do for older shimano 600 hubs that run a little noisy?