I have a set of 410's now. I'm wanting to get a set of 354's. Any idea's?

If it's the truck in your sig, chances are you have a 14 bolt 10.5" full floater. And 3.54's will be REALLY tough to find(don't think they ever offered them with that diff), but 3.42's are easy to come buy and was a factory option on some.

http://www.4wheelparts.com/4wp/products/productLine.asp?cat=DRI&prodline=272&catName=&man=GENU&parentProdline=DriChevyGENU&expand=sub1