Hey Ed, my dad has the same truck and his rear main seal is leaking also. Its been doing it for a couple years now. When it first started I did a google search on how to replace it and from what I remember it would have been better to take it to a shop that has a lift and let someone else to do it cuz the tranny had to be dropped. I was going to do it for him but Im tired of always crawling under the truck. Replacing the seal didnt seem to bad to do just didnt have a lift. Let me know what route you go.