Guys, i just bought a 2008 silverado Z71 with 23k miles on it ( see pics in Vehicles thread).I changed the oil today with Synpower 5w30 and AC/Delco pf48-E. Plans are to change the Transfer case fluid with the GM Trac II as it has the Auto 4x4 feature. Also plan to Change both Differentials with Synpower 75w90 GL-5 and service the transmission by dropping the pan and replacing the filter and 5qts dex VI fluid. The differential is a locking diff with 3:73 ratio. is this a G80?? Question is...Is it too soon at 23k miles? should i hold off a while or go ahead and service it all now? Unfortunately the previous owner (first onwer) lost the manual so im not sure of the severe duty schedule. Thanks!