would the bed of a 1999-2002 silverado stepside fit a 1988-1998 c/k ruck?

Go under it and measure away ! Check front mounting bolt to front of bed, bolt to bolt measurement from left to right, bolt to bolt front to back and last bolt to end of bed measurement. Check fuel filler neck and bed cross member locations to see if they match. OR you could go to your local auto recycler and have them look it up in their Hollander Interchange Manual to see if it works.