So I'm driving the 72 today and it pops out of 4th gear, that's never happened before. So i stopped by the shop and discovered that i was very low on tranny fluid, we refilled it and on my way home i had to hold the shifter in 4th so it wouldn't pop out, i could still feel it trying to pop out and sounded like it was scrapping the gears. I pulled off the highway and drove the back roads in 3rd to get home. What's the deal? Is my transmission going out? Clutch? thanks, jeff