I would also say that your trans is likely shot, having the Maggie on there adds alot of torque, couple that with a heavy curb weight and the fact you said someone before you ragged on the truck a bit... Im not surprised it failed. A shift kit alone may have helped it live a bit longer but there is much more to properly beefing up that tranny to handle the extra power. Sucks to hear that it failed on you. I would find a reputable shop in your area that handles performance rebuilds.
Best of luck in getting it back on the road soon
