Not really even sure how to explain this problem. The other day while driving the car made a loud grating noise, which would stop if I kept giving it gas, but would persist while braking or simply slowing down naturally. This continued until I reached my destination (drove fine), but when I got home, my reverse gear would not work. I tried putting it into 4wd, and reverse worked again (and also in 2wd). What on earth is wrong w/ my truck?