1993 80 series Gear Box & Transfer Case

Hi Guys,

I would like to know if anyone can help me. I have a 1993 80 series part time 1HZ Std Cruiser with 400,000km. The problem is that when you back off the revs in 5th gear, it will fall out of gear and then you have to put it back in gear.

Also I am having trouble trying to get into low range on occasions, if not used for a few weeks or so, it gets very hard to engage low range, but after used it is ok for awhile.

I was stuck in muddy water for a while and flooded the 4wd and this low range problem has just started since then. I had the all oils change the day after I was stuck in mud.

Am l due for a rebuild or is there any thing I can try or do to stop falling out of gear.

Thanks in advance for all your expert opinions.

David