I drove a '94 Chevy with the overdrive before my current '04 GMC D/A. The '94 had overdrive and no overdrive on the steering column. I would drive that truck in no-overdrive around town in stop and go traffic and also when pulling. I drove in overdrive on the highway, unloaded.


What are the recommendations on driving the Allison? Is it the same? When in Tow/Haul should you also turn off overdrive?


PS. I just found the no-overdrive option on my truck.


Thanks for the information in advance!

Run in overdrive unless you are pulling heavy and its doing a a deecent amount of shifting and "hunting" for gears. If it isnt downsh*ting a bunch or at all leave it in OD. Or if you are running hot EGT's becasue staying in OD is lugging it a bit(probably only a deal if you run a program) putting it in 4th can cool the egt's a bit.


TH is very nice when pulling since it will keep your trans a bit cooler and the grade braking is a plus.

You cant put your truck in 4th gear unless you install an overdrive lockout switch. I would leave it in overdrive pretty much all the time. Their are some exceptions as noted.

To make the LLY do OD lockout, hold the button for a few seconds.


T/H is useful when driving in stop and go traffic when unladen. Makes it shift less.

Oh, do to the gear spacing and ratios, there is no reason to use the OD lockout unless it hunts on hills when towing.

You cant put your truck in 4th gear unless you install an overdrive lockout switch. I would leave it in overdrive pretty much all the time. Their are some exceptions as noted.

I know at least on the '04's, you can lock out OD on the column. Push the button for T/H, push and hold for a second for OD lockout.

Marc

03's are the same as above.