The other method is to pull the shifter to add the extra quart of oil. I do it this way. Between the exhaust, frame, front drivehshaft, t-case linkages, its just much easier to pour it in through the top.
My first getrag went out under warranty at about 60,000 miles. Front bearing on the countershaft failed. This getrag has been running well and currently at 210,000. I would have to say life has been rougher on the second getrag. Been running around for quite a while with large tires, more smoke, and lately larger injectors, PLUS I tow heavy, and in overdrive when the truck pulls it right.
Don't lug the truck, let everything spool more especially in towing.
Change the oil often. I run about 10,000 miles a year or so, and change it yearly. As stated above I tow heavy most of the time.
I don't think its bad transmission, just speced too close to what the cummins puts out. Hopefully I can get a 6 speed to put in my truck.
Michael