Been driving my 91 F150 for about a year with no sign of problems. Yesterday as I drove under an overpass I heard all I can describe as a big can full of marbles being shook. as I cleared it I didn't hear it so I thought it was work being done overhead. About 2 miles done the road the truck just races and no go. Well it's 100 degrees and I roll to a stop miles from nowhere. I figure I have nothing to lose so "Pray Hard" and put it in 4low, it's goes but I have to hold in in 4 low while nursing it at 2500 rpm doing 30 through every back route I know. I'm thinking I blew the High gear in the case, but I have zero experience in this situation. Any thoughts would be greatly appreciated.
Fred