Dear SC:
How about adding a new column to the table containing an appropriate
datatype for your product ID. I recommend making a unique index on it. You
can remove the existing autonumber whenever you have the new column set up.
Do you have any existing dependent tables? If you do, you'd need to add the
product ID to that table as well, and build a relationship on that. When
you remove the autonumber, any existing queries, and possible code or forms,
that use the old autonumber will be broken until they are changed.
Making a change like this after deployment will be a real challenge!
Tom Ellison