Sorry about the hiatus lately guys. Been working 12+ hours a day on the dang ship and dealing with a new addition to the family and the wife. Now before anyone thinks we had a kid, no its a purebred Golden Retriever. I'll put pics up in the coffee shop. But for my question, I found a pair of heads that supposedly came from a running engine from a 2003 Sierra 5.3 for 85$ for both of the pair. I know my engine is getting old and is starting a case of the early morning/cold weather knock. Would heads from a 2003 5.3 fit a 99 5.3 engine? Is it worth buying and swapping them out at all?