1988 me disengages 4x4 under load L4

[duf_beer]

km145 gearbox dunno what transfer disengages under heavy load in L4 right when you need it, is there a safety mechanism? this is exactly what happens - usually 1st or 2nd gear up steep hill requires L4, get almost there and right at the point a loud tink and ping, completely disengages and clutch wont work then reverse down put her into first and back to normal? what the... this is why I asked if there was a safety mechanism, drives fine in every other respect one of the best around love the thing want to fix it will put pics up lots of work done, more to go. Any help or references would be much appreciated thanks.

[bundyjr]

1st gear is being driven out of mesh based on what your saying( excess wear) had the same thing happen with a 88 2.6ltr 5 speed 4wd triton i had only diff it was 3rd that would fall out under load. rebuild time