Need tables to translate the 3-digit 1990 and 4-digit 2000 census occupation to a prestige index

USA
1

By prestige index I mean something like the Duncan index

2

I am not certain what kind of tables you are looking for. Currently the IPUMS-USA project does produce a number of Occupational Prestige variables based on consistently coded occupations over time. The “Integrated Occupation and Industry Codes and Occupational Standing Variables in the IPUMS” page goes into greater detail about integrating these variables.

I hope this helps.