what makes my transmision shift fine through first,second and third then when it shifts to overdrive it just revs up and slips
Your overdrive band (aka 4th gear) in the transmission is burnt or glazed. Time to start saving for a transmission rebuild. In replacing just this band, your best bet is to replace all the internal bands, seals, while you have it apart, hence a rebuild. I think you can lock out the OD on your vehicle in the meantime?
I did not have the overdrive plugged into the transmission correctly when I installed it and drove the truck for atleast 8 miles. Is the transmission destroyed?
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