O/T Allison Transmission trouble in 03 duramax

I'm looking at a truck coming up for auction. They said the code came up and told them the transmission was slipping due to module, transmission shifts but doesnt have overdrive. I believe it has a banks 6 gun tuner. Does the tuner put the transmission in this mode at a certain power level or does it need a new tranny?

Any insight appreciated, I think i can get truck cheap but dont really know what im getting into.

Thanks

It could be something electronic or solonoid related, but being an older model with a tuner I would say it's in need of a rebuild. The Allison is a very reliable transmission at factory power levels but when you crank the power way up with a tuner fifth gear is often the one that goes first. BTW a rebuilt Allison is going to run 4 to 5 grand if you install it yourself. Check out Diesel place. They have a section devoted to the Allison transmission, very helpfull.
Diesel Place

I've always been curious about that Allison that gets used in pickups behind that Duramax. Allison is known for their trannys, at least in big trucks. I wonder about that little one, and don't mean that as a slight to it or any of its users or owners. Here's my point...I have an '02 Cummins Dodge with an automatic too, and I don't use it often. Love the truck, bought it new, this one mostly doesn't get used and sits in the barn. I just hit 60K on it, 30K of which I put on it last year, easy miles...and just had $2,700 in work done to it for new torque converter and other stuff coming apart. That's the second major repair by 60K miles, the first one at around 25K and warranty by the factory, not the second one by years...just missed it. That Cummins is a great engine, backed up by no trans. Should they have backed it up by an Allison maybe? My '96 just keeps going, and going, and going, but manual trans. I love the manual trans and if one was on the lot when I bought the '02, wouldn't be asking about Allisons and wouldn't have been into a second major at 60K.

So to you Allison guys, is it worth it? Does it take what that Duramax gives it? I sure hope you guys have better luck with your automatic than I've had with mine.

Mark

I believe it has a banks 6 gun tuner.

Theres the problem. It didnt do anything to the trans., but the extra HP to the engine did.

What I have been told is that the Allison will hold up to anything you throw at it within reason. Usually the torque converter is the first to go but there are many aftermarket ones that are made for pulling, drag racing, and such. One thing that Diesel World always says is that if you are going to invest into adding horsepower don't forget to invest in the trans. programmer.