transmission?
 

Thanks again to all the bombers who have helped in the past.

I have recently put some time into my truck and changed tranny fluid and replaced sensors. Found snap ring pieces in my pan (thanks for the help identifying in my previous post) but not sitting on the money for a rebuild yet. Truck has actually been running and shifting great even into OD. I have also replaced rear wheel bearings and seals, and front and rear brakes.

Today leaving a stop light, I pressed the pedal (1200 rpm) and nothing happened. Let off and lightly tried to take off again. this time the truck shuddered and then slammed forward with a loud clunking noise. for take offs after I put the truck in first and manually shifted through the gears with no problems. even a few take offs in drive with no problems.

My question is, with the many things I have done to my truck, does this sound more like the transmission, or could I have assembled the rear axle wrong, or something completely different?