GEARBOX LOSS OF DRIVE

[DiscoDuck]

Coming home tonight gearbox started to make a grating sound , "same in all gears" ,then transmission started snatching, eventually got so bad i had to pull over .
I tried to move truck forward and back.
More snatching and a little movement and a sound like drive cogs loosing contact with each other as truck lurched forward or backwards.
Same in Hi and Low range ,no difference with "DIFF LOCK" in or out.
RAC towed me the 5 miles home,
(all levers in neutral engine running).
towed with no noise and as sweet as a nut.
managed to reverse onto drive with RAC man pushing.lol.
Any thoughts as to whats gone wrong and any tips as to where to start looking.
300 dti manual 1997 ...193k

[Saffy]

worn out splines on the lt230 transfer box input gear, though unusual for a 300tdi.... maybe someone put an older transfer box on it at some point.

[andyb]

I don't think it is as black and white as 300Tdi have the spline wear fix.

You need to check the transfer box suffix letter. IIRC the F-suffix boxes are the 'fixed' ones.

Anyway, I also vote for the spline wear issue causing the problem.

You will need a mainbox rebuild to replace the main shaft and likely the input gear in the transfer box itself.

[Saffy]

if lucky the mainshaft splines are okay, so can get away with just the input gear.  People swap transfer boxes between models /disco/defender/200tdi/300tdi to often to be sure what's on there without checking