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Message: <blockquote data-quote="GaryM" data-source="post: 30540" data-attributes="member: 9373"><p>Actually it's a 6 spd with two overdrives to give you 7th and 8th. The TCM is very sensitive when it comes to shifting to 7th and 8th and there are a host of things to consider. I found out the automatic trans fluid was not warm enough to allow the TCM to shift. Normal ATF on highway temp should be 175-215 deg F. Mine won't go above 140. The TCM threshold is 150 so it won't shift to 7th or 8th. It may go into 7th in light load (downhill and no throttle) and it may stay there for a while but eventually it will shift back to 6th. I'm working with the dealer to replace the thermal control valve for the transmission heat exchanger. If they stick closed the trans fluid never warms up. We'll see how it works after that.</p></blockquote><p></p>