A decent 2.6 manual tranny can hold up quite well. There are a few things that can go wrong but if you address those you should have a very tough unit.

First off any manual transmission has an inherent weakness. The gears produce metal and the ball bearings get damaged from running through it. On a bearing that is highly laoded this can greatly shorten it life.

I have gotten front bearings that were sealed to prevent this from happening. The input shaft bearing seems to be the most sensitive. A rebuilt unit produces less metal so is should last longer (the gears have been run in).

The 2.6 transmissions can pound out the thrust plate for the main-shaft and the counter shaft. The metal used was soft and allows too much endplay over time. This makes for a noisy counter shaft and when the main shaft moves it causes the tranny to pop out of gear when you let off the gas and also puts a lot of metal into the oil since the shifter forks are rubbing a lot. There is a TSB on this plate / problem (I think there is a better part available).

On some transmissions the retaining nut on the main-shaft works loose. This appears to happen from the parts that are clamped taking a bit of a set, reducing the clamping. That gets parts pounding and lets the nut back off. Never ever try and tack weld the nut to the shaftà The shaft will break.

Use a new nut when you put the unit back together and use loctite on the nut and the bearings. Make sure you pean the locking tabs.

Use a die grinder to take the old nut off, just grind away the area around the tabs.

The last issue is the OD gear. The hub and the gear are welded together (most transmissions do this thatÆs how you can cut gear teeth very close to the synchro hub). Some of those parts are defective from the factory and break from stress points created from the weld. If you have a good gear that lasted that long it should keep on working. New OD gear sets has been known to just blow up. The new part is a new design that must be changed as a set. Perhaps this is a good candidate for cryogenic treatment?

I have used the manual tranny with a turbo motor and it never broke, that was at 250 ft lbs of torque. A better description would be it wore outà

Most of these problems happen over a very long time and most units last at least 125,000 miles. Personaly I like the standard trannyà The performance is good as is the fuel economy. The auto is slower and you lose 2 mpg. Adding a lockup converter auto fixes most of those problems but that is a big conversion.

I would stick with what you got (pun intended) and see if you can find a shop that can go through the unit or score a good used one.

Kevin