Had the same problem with my Early Bronco...thought I'd blown the tranny(Reminded me of breaking a chain on my M/bike years ago..same feeling!)
Turns out...the high - low shift on the Bronco had slid into neutral.
Took me days to figure it
I havent look at my VX hi-low shift to see if it can happen ( its in the muffler shop as we speak)...
...but Im wondering if this could be your problem?
jo