Hello Vaeagleav and thank you for the info. Anything and everything helps at this point since I am seriously ignorant about this Avalanche but getting educated hourly. I bought, brand new a 04 AV 4x4 in 04. I didn't get around to getting to know her that well. Nasty divorce forced it out of my life but I swore i'd get another, A bucket list thing. I'm retired now and couldnt pass this one up. 04 Z66 in white, like my last one, leather, all the options that I don't need, like folding mirrors and heated seats and it had only 78k miles. Some rust cause it spent most of it life in New Jersey but in overall dam good condition for a 16 year old AV. Now im trying to learn everything, RPO codes etc because I want to put the best parts into this AV. I plan on taking her to Valhalla when its time to go. LOL. From reading lots of posts I beleive that the stock shocks are in fact Bilsteins. In fact the shock on it now are blue on the top stage. Cant tell if its yellow on the bottom tho. Too much rust.