Outer Limits 4x4 Board

Hi all my girlfriend is having trouble with her 94 isuzu mu 3.1lt

the problem is in 4x4 going up a hill it slips out of low range

its standard no lift no body lift

im trying to work out what it could be but nothing is coming to mind.

Cheers in advance.

Check you engine mounts and gearbox mount, also check the gear stick rubber surround it may be holding it back (in the way)...

Is it auto or manual?

its manual.

and thanks ill check those out