I have a quick question and I can’t seem to find anything on the internet. I have a 2003 350z with rear driver side Quarter Panel damage. A guy wants to sell me a rear DS QP with the same color in perfect condition but its from an 06 350z… Will an 06 350z rear driver side QP fit on a 03 350z??
I would suggest calling a salvage yard in your area and ask them. They have cross reference books that will tell them in a second if it will fit up.
Yosemite
I have talked to many salvage yards that do not have 350z in salvage or know anything about what I am asking them. I’ve even tried salvage yards in the next state over and still no luck. The guy that is selling me the part is parting out a whole 350z
The sheet metal looks the same between the 03 and 06 350Z.
Enter 350Z into a search engine and then click on images, and you can compare the rear quarter panels between the 03 and 06.
Tester
Is a body shop going to install it? They should know the answer.
You can also use the eBay search feature with body panel and salvage yard sellers. Think of it as a free Hollander Interchange… 
A quick look shows the 2006 is compatible with the 2003 model.
Regarding interchange manuals, some city libraries often have a Hollander Interchange manual in their reference section. It’s something to consider when info is needed about a body or even a mechanical part.
It looks like the part number is the same for 03-08, but I would just call the Nissan parts department and ask to compare the part numbers of the two years. If they are the same, no problem.
Thank you guys so much for all your help!