Vehicle has about 130 thousand miles, and has been well maintained. About a year ago the dealership did a complete flush of the transmission fluid (it was fluttering @ 30mph and 50mph). Vehicle has been fine until last night. We returned to our vehicle from a trip and started it up and when I put it into drive it was hesitant. I pulled the truck forward put of the parking spot so I could load up the kids carseats, and when I put it into park the vehicle made a grinding, clank noise. I tried to drive the vehicle to the nearest gas station and the transmission slipped in and out of gear the entire way so I turned around to where the vehicle was parked originally. The branch wouldn't allow me to shift into D3 or D2 or 1. At one point the vehicle was completely stalled not being able to move forward or backward. The transmission fluid level was ok and the color was ok and I did not notice any burnt smells. Had the truck towed home and the tow truck driver drove the vehicle off the ramp! When I asked him how he got it on he said, "I drove it up there." Then he said, "it was probably cold fluids." I am at a loss of where to begin to troubleshoot and I don't want to take the vehicle back to the dealership. Any thoughts, suggestions or ideas would be much appreciated. Thanks in advance

update* check fluid levels and they are decent but smell burnt and fluid color is a blackish-red. Temperature has been in the 30s and 40s.