With my 97 F150 and 3.08 diffrential the converter does not lock up until 33/34 mph. If you are towing a heavy load or climbing a grade you want to be sure you are above this speed and do not drive with the transmission unlocked for any period of time. The transmission fluid temperature will get too warm. If you do have to tow at this speed better get a good transmission cooler.

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97 4.6 F150, 1/4 = 17.48 @ 82.2 mph, 88 5.0 Mustang 1/8 = 7.409 @ 93.72 mph


[This message has been edited by LarryS (edited 08-05-1999).]