I have a 2002 expedition.4.6 engine. Was told transmission is going out. It sound like a barrel of bees going down the road. Forgot to say it is rear wheel drive. It is not slipping,just very loud going down the road. The mechanic that told me this does not work on transmissions. Should I get someone look at it that does? I use this same one for all other problems with our trucks. If I have to get one what do I look for for one to fit? Thanks