Please Help??

I have a 110 defender 1998 300tdi, its the first landy i've owned and i don't know too much about them so could anyone figure out whats gone wrong with it? I was driving up the M1 doing 85 when it started slowing down, it was still in gear and my foot was pushing the accelerator but it just started losing power?
Its now parked up at home but can't move, It starts fine and goes into every gear except the high dif, if i take my foot of the clutch while in gear nothing happens ie, it doesn't stall?? has anyone experianced this problem? if so please could you shed some light on what it may be? I've been told it could be the thrust plate or the transfer box or the gear box?? Cheers.
Paul

I have a 110 defender 1998 300tdi, its the first landy i've owned and i don't know too much about them so could anyone figure out whats gone wrong with it? I was driving up the M1 doing 85 when it started slowing down, it was still in gear and my foot was pushing the accelerator but it just started losing power?
Its now parked up at home but can't move, It starts fine and goes into every gear except the high dif, if i take my foot of the clutch while in gear nothing happens ie, it doesn't stall?? has anyone experianced this problem? if so please could you shed some light on what it may be? I've been told it could be the thrust plate or the transfer box or the gear box?? Cheers.
Paul

have you tried driving it with the difflock engaged? If it'll move with the diff locked then it sounds like you may have snapped an halfshaft

You'll have to be a bit more specific.... Did the engine loose power or did you loose transmission. Doe the transfer box go into difflock but not high ratio and if so do you have drive in low ratio with difflock engaged and disengaged?

Cheers guys for the info,
I finally got round to trying Snagger's idea of getting it rolling! Unfortunately it didn't get it sorted, However i did find that it would engage the 4th gear and move forward when in low dif and drove it round the block.
Needless to say it still goes into all the other gears without having to use the clutch and doesn't stall, but nether did it drive in any gear but 4th i had to use the clutch to get in 4th gear just as you normally would and the clutch seems to be worknig just fine. Each time it slipped into all the other gears i could hear the teeth rubbing together slightly but they just don't seem to be catching? the transfer box seems to be working ok as it now goes into high, low and dif lock a little on the stiff side but they went in.
Unfortunately i didn't get round to checking the ATF level, would i do this via the small bolt on the side of the gearbox as there doesn't seem to be dip stick on the 300tdi??
So i'm still no wiser as to what the problem is! many thanks once again but any other tips would be most welcome.