B3000 Automatic Transmission-NO FIRST GEAR HELP!!!

[half_ex]

Hi,
I have a 2000 B300 Mazda truck. I love it and it runs great till today. I was driving through some mud and got it stuck. Well me and my ego I thought I could rock it out. This is an automatic so I was shifting on the colum between D(Drive) and R(Reverse). It was working but then I put it into D and it dosen't go foward anymore. I didn't hear any bad sounding noises or anything. Everything else works fine but the first gear. When I put it into D it just sits there. So to get it rolling I put it into 2 get some speed over 10 mph and put it ino drive and it will go through all the great up to OD and down the highway no problem. But once I stop I have to stick it into 2 and back into drive? I obviously know that my tranny is sick and its going to cost money. Now is it simply that it overheated, or maybe a filter got plugged? Did I completley shredded that gear clean, and if I did do I have to replace the whole tranny or just the one gear. I think changing the one gear is cheaper. Looking for advice or maybe a simple remedy. Thanks

[mazdatech]

2000 huh I would take to any ford or mazda store and have them check for codes with their WDS machine (specific obd2 tool for ford/mazda and go from their but it does sound like you smoked it how does the tranny fluid smell/look? burnt black yup its done