shift points for tranny
 

I have an '88 F250 XLT Lariat with a 7.3 International IDI diesel and a 3 speed auto tranny. Bought it from an old guy, the original owner who had it set up to tow an 35 foot 5th wheel at about 10,000 lbs. Shows 200k. It was his pride and joy. Mint condition. Every option available in '88 and they all work. Runs like a swiss clock.

He installed a Gear Venders unit which I understand gives the truck a high range. When I engage it the revs drop about 25%. When I turn it off the revs jump back up. He said it has a Dana 50 positive traction rear end. He gave me the original bill of sale and a shop manual.

It gets about 20 mpg on the highway at 90 kph. I use it to tow a 3500 lb travel trailer which it does with no trouble. Even in high range the engine seems reved up too high. The tranny shifts at 27 - 28 hundred RPM. I suspect the old guy had it set this way for his 10,000 lb unit. Mine is only 3500.

Anyone know how to change the settings to get the tranny to shift at 23 - 24 hundred RPM?

Thanks

when i tow something i don't use o/d unless i.m on a flat strech of road.i all so have a manual trans. but have towed with an o/d auto a few times and found that the auto will shift up and down all the time.so i just use drive.