We just had a massive snow storm and we run snow removal operations for a bunch of customers. I pull a trailer with the skid steer that we use so no plow on the truck. Friday night finishing up for the day and I go to leave the last job site, put the truck in drive and it doesn't move. 1st gear was lit up but just revved up like I was in neutral when I would press the gas pedal. It went through the gear numbers on the dash and then stopped on 5, heard a clunk sound when it engaged, and then the truck would move. Wrench light came on, it stays in 5th and will shift to 6th when up to speed, but wont downshift when slowing down. Reverse works just fine. I put it in the garage all night and all day yesterday with the salamander heater going hoping to warm up the truck and thaw it out. I thought maybe some ice froze up on some connectors or something. Tried again this morning and still same issue. Any advice or help at all?