lt77 jumps out of first gear.

A up all,

as the title suggests my problem is when going down hill either in low or high box, first gear will work its way out, no crunch just pops out into neutral. All other gears are fine (even reverse). I have found no information anywhere relating to my issue. The box is off a military 110, reconditioned in 1997 as stamped on, fitted to my 1988, 90.

Any info would be appreciated.

Regards, Ben

first gear dog teeth will be worn

So thats a box out rebuild job then?