Hi everyone. Allow me to introduce my self. My name is Tom Sutan and recently bought an 86 4KCSQ from the 1st owner. Im going thru all the fluids now, but have a question regarding center and rear diff oil replacement on which grade to use. 75/90, 75/90NS, 80/140 ? BTW im going to use MTL for the tranny. Please give me some pros and cons. thanks in advance. Tom