RPM's hit 2000 in 3rd then it drops to OD at 45mph dropping the rpm's to 1500-1600. Now to maintain 45-50 on small rollling hills you need to press down on the throttle more than with the GM 8 it had stock and I think the conputer see's throttle position and just downshifts to 3rd.
My truck is...
After owning the ATT for some time and putting some miles on it I have found a downside to it. Lack of boost at 45-50 mph. I am up in NH and there is a lot of rolling hills where your speed is around 45 and the lack of boost requires more throttle input which results in the truck wanting to...
I have had good luck with the stock gm one. The factory one lasted about ten years with commercial plowing, replaced it with a stock replacement thats still going.
There isn't a tire maker out there that hasn't suffered the same issue at some point. It happens. I have been using BFG's for years with no issue's.
Maybe the tire was under inflated, was cut from something, damaged during mounting, many things can be wrong here.
Just wanted to add one important step. Unplug the transmission otherwise when you lift the engine the connection will hit the shift linkage for the t case.
The leak turned out to be the fitting broken at the housing where it threads in. I have a new fitting from the dealer. I use a screw driver to split the broken threaded section in half and pulled the pieces out, I am off to borrow the tap to run through and clean it up nice before putting it...
Measure the size of the knuckle between the ball joints and check the tapper on the ball joints. Maybe you can swap the whole knuckle with the brakes onto your truck. That would be very nice.