I sent my truck to the garage to have brake line's replaced and transmission serviced . Before I sent it to garage ,I had front wheel speed sensor codes and radio speaker codes but truck run fine and never had ANY transmission problems . When I got my truck back , I had drove it for about 10 day's when out of no where , my transmission jumped out of drive . I pulled my truck over and it acted like it was in neutral . If I manually shift, I will have 1st gear with no problems , second gear has a scrubbing noise from about 10 mph to about 25 mph and the noise stops , I can shift into 3rd gear when I get to about 40 mph and it runs as if nothing is wrong until I drop back down to 40 mph and there it Slip's out of gear . There's no Drive but I have reverse. Only code that is shown that I didn't have before I went to the garage is for the rear speed sensor and I changed that sensor but still have the code. The right front bearing and speed sensor are almost new and it had that code before I went to the garage . I can't find a bad wire or connection for the sensors. What's causing my transmission trouble ? I thank you for your time in reading my post.