Had a drive with the centre panel removed today and the squeak does sound like it's coming from the transmission area, I had a check of the fluid in the gearbox and transfer box and both seem fine. I fairly recently drained and replaced the rear diff but I have not checked the front for a while.

Vinlander said:

Where is your squeak coming from? May be a belt, but you'd likely hear something at idle too. Have you tried driving with windows open?
If under acceleration and not revving idle, should be a drivetrain component. Wheel bearing, stub axle, halfshaft seal, gear/diff oil, etc?
Sticking brake or loose calliper? Wouldn't feel it in 1st or 2nd, but would become more evident when under strain.

Click to expand...

Is it fixed yet?

Tonym3 said:

Had a drive with the centre panel removed today and the squeak does sound like it's coming from the transmission area, I had a check of the fluid in the gearbox and transfer box and both seem fine. I fairly recently drained and replaced the rear diff but I have not checked the front for a while.

Click to expand...

Definitely do the front diff. If anything it needs it more than rear. Grease your UJs and props while you're under there, and check around the transfer box and diff flanges for anything fouling them.

OK update time, I feel a tad embarrassed as I was convinced it felt like an fuel or air issue,
However the curve ball turned out to be the judder under load, this was not as I thought a result of the loss of power but Infact the root of the lack of Power.
I had a couple of mechanics drive it and the second commented that he had been able to power through the judder, which made him look straight at the rear prop and the UJ which as expected was wobbling like a good un!!
So I ordered a couple up and took the rear prop off one lunchtime gave the same mechanic a drink and he fitted the new UJ's ( I tried but soon gave up!) then I popped it back on and it's been running fine since.

Two lessons for me
1. Don't try and find the tricky fault when it could be easy.
2. Mechanics have a whole load more experiance than me and Google!!

Thanks for everyone's help on here it's always hard to try and diagnose with just a dodgy discription but I have a load more things to change and look at thanks to all the answers.

That's what's wrong with mine. It's OK for fifty miles or so after I pump the UJ with grease

Vinlander said:

That's what's wrong with mine. It's OK for fifty miles or so after I pump the UJ with grease

Click to expand...

Changing the UJ's was a pain in the arse hence why I gave the mechanic a drink to do it, still only took him under an hour to change both, then bolting the prop on and off was all of 10 mins work well worth doing the job.

One thing at a time .. swivels and brake lines are a safety issue.
Haven't had it for long, so it's all a bit slow, but getting there

Vinlander said:

One thing at a time .. swivels and brake lines are a safety issue.
Haven't had it for long, so it's all a bit slow, but getting there

Click to expand...

could argue that the prop is a safety issue if it lets go, locks up your transmission or digs into the ground and causes you to crash.

It's on the list.
I have it all in order of propensity to kill me, and I'm a pretty good judge of character.

Can I have "I'm a pretty good judge of character" on my tombstone?