The light bulbs will fit. The light cover will not. Chevy and GMC while basically the same truck, have different headlights, taillights, and grill. The cover piece on a chevy is more vertical, while on a gmc it's more horizontal. You will need specifc covers for each make. The light bulbs however, just plug into the hole, and are standard issue.
Edit: This is specific to the 2000 model year you asked about. I believe this answer is valid for any truck 98-06 and includes the 2007 classic body style.
2nd Edit: After rereading your question, I see that your not talking about swapping it from silverado to sierra, but from a suburban to a sierra. The answer above still applies. The headlights on the Sierra are a bit more rounded, while the headlights on the Suburban are a bit more square. You could like swap the headlight off of a Yukon, they should be same.
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