I have a 91 80. It has about 200k on it. It has been very slugish and not shifting for about three months. I treid a fluid change, worked for a week or two and then back to slug. Called a mechanic buddy and he told me to try a cleaner. Now at the local dealer they sugested a flush and clean ($200). Not bad. Well, My freind said to just go get a transmission addative. Picked up Seafoom. While I was there picked up some injector cleaner, oil addative(She had a small amount of ring blow by), and some lucos oil for the front diff. Total Charge $30. Droped the addatives in the truck before leaving the parts store. Sunday did the front diff. This morning on my way to work I thought I was driving a sports car. All in all best Thirty dollars I ever spent.