Gearbox Woe

Pottering along today lost forward motion. Coasted to kerb.
In 2wd in gear no go whirry noises.
In high ratio all gears working -4wd
In low ratio all gears working - 4wd
What has failed in the gearbox for this to happen?
Any replies much appreciated as long as they are constructive.

a rear half shaft id think if 4wd gives motion

second James on the half shaft.

or a shot drive flange on rear axle perhaps?

Pray that it is a half shaft, cheap and simple job.

Sounds more like an axle issue than gearbox

Very encouraging, what's easiest way to check?
I'm assuming jack up back end and rotate wheels - that's as far as my diagnostic ability goes!
Or pull off wheels hubs etc, draw shafts and look for stripped splines or full breaks in shaft.
Ta,
Tom

put in gear in hi box 2wd and see if rear prop spins

Gentlemen,
Many thanks for advice, right hand shaft is the culprit. The splined end no longer exists, assuming stuck in diff. I did push left hand shaft into right hand side to check whether spline end would engage. No joy
My inexperienced logic says:
Disconnect propshaft, open diff see if I can get shagged bits out. Can I do this job with axle in situ?
Looking forward to skinned knuckles and wet back.
Tom

You can work on axle in situ. Probably easier if you back it up onto a decent set of ramps to get decent clearance underneath for working.

By splined end do you mean the drive flange has had its splines stripped or the splines in the diff?

A magnet on a stick can help sometimes that's how I got mine out...

Not a difficult job but awkward. Drain diff, drive shafts out, propshaft disconnected at diff and tied out of the way, retaining nuts off, diff off. Careful, it's heavy. Tap out the end of the half shaft, clean all the bits out of the diff and case, consider replacing the oil seal if it's been leaking (it's easier than doing it in situ), refit the diff (you might need help lifting it in) with a new gasket (worth a bit of sealant here) reconnect propshaft, replace BOTH halfshafts (the other one will go shortly as they both fatigue, they are designed to fail where they do so you can get the diff out...) using new flange gaskets (plus sealant - I wish I had shares in the company that makes hylomar) REPLACE THE FILLER PLUG before refilling with EP90 (or the closest you can get). Job's a goodun.