Just had my transmission, transfer case, front and rear end changed out to Synchromax. Anyone else running it and what how has it held up?? Did you add any thing to the rear for the limited slip?? I pull a 14k gooseneck on a regular basis. Called RP and they said no additive needed and I could use it front to back in my 2003. How about RP in the Cummins?? Currently using Amsoil... I know a million different opinions on that one but would love to hear them... I live in South Texas where it stays fairly hott year round and also have a heavy foot and usually like to take it to top speed on a regular basis. Hope that helps out some. . thanks