At about the 160k mile mark, it seems that the "forward sprag" in our automatic transmission broke according to the research I was able to do last night. The truck only moves in 2, 1, and R, nothing happens at all when putting the selector in D.

- Our truck is a 2006 3.5L and a keeper. What's the best/typical way to go about getting the truck fixed, have our existing transmission rebuilt or drop in a whole new Reman as a unit?

 

I would rebuild your stock transmission if at all possible but do not waste the money on stock components. Take the time and do some research here:

4L60E Performance Transmissions from PATC

I would call them and see what they think. As Im sure you know, you have a 4l65E transmission. This is the youngest sibling to the 700R / 4l60E family.

They should be able to either send you a rebuilt transmission or send you a package of rebuild parts/ upgrades that are tested to work together. You could then take the package to a local transmission shop and have it rebuild.

 

Good to know the stock unit might last to 160 k.
If/when mine goes at 160,i'd try to duplicate the stock unit!. No tinkering for me.
I'd be happy with 160k.

 

Since we cant gear the front diff any lower due to size constraints, would we be able to install a lower ratio 3/4 gear? I see they mention a HIGHER 1/2 gear set but I want lower not higher gearing for a bigger set of tires. Especially in top gear.

 

I think thats kinda rare. I would not tinker with the transmission either thats why I am saying just buy the package that has been time and time again tested to make the transmission last and work together as a "kit".

On my last 2006 h3 my transmission was slipping at 70,000 miles.

If you scroll down about 1/3 they have a hummer h3 section. A fully built transmission from them for our h3 is $1899

 

sweet link

 

Since the truck is my wife's daily driver and it's Christmas Season repair time is an issue, we went the dealer service route. $3k out the door with a new GM OEM transmission installed.

If this one lasts as long as the original too, I'll be happy.