L322 TD6 2003 lumpy and hesitant at 50mph - in France.

Torque Converter and/or Gearbox -
I have read many posts on this subject and I am just trying to confirm the problem here.
Having briefly taken off at maximum acceleration (!!!), a vibration has started which I can only describe in two ways.
1. Like driving over small bumps in the road - when it occurs - and only sometimes.
2. The car doesn't know which gear to be in and hesitates, jumping and hiccuping between two gears. This is all the time at around 1600-1800 rpm at around 50 mph (80kmph on my french speedo obviously!). Feels like a misfire, but it does not occur under load, where it pulls fine. Up hill and down hill are all ok. Just when cruising at flat throttle 45-50. No other times.
It happens at 45-50 mph. 60-70 is fine and low speeds are fine. I normally take it very easy on the pedal.

I did have the Trans safe mode warning come on once a few months ago. But it went off on restart and has not appeared again.

So after reading here, I am presuming the following -
1. Drain GB. If metal in the oil, then replace TC. Flush and refill GB and cross fingers.
2. If a lot of metal in oil then can't cross fingers, fork out €€ and ££ and replace TC with HD TC from Ashcrofts and replace GB with a rebuilt unit.
And thats where my problems start.

Anyone know a reliable gearbox rebuilder in France - between Pau and Bordeaux, or further afield - or am I better off getting a pro in the UK to do it and ship it over?
Sussex Auto Parts will turn my TC around in 48 hours so I can fly over with that.
Should I start with the TC and see how it goes - or better off biting the bullet now?

Transfer box motor - could this be part of the problem? Is this part of a GB rebuild or a separate thing?

Also open to any other suggestions.

Update -
I have been onto the LR guy in Pau who wants 5200 euros to supply and fit rebuilt box and new heavy duty TC. Thats £ 3800 which sounds less than 5200 but is still quite a lot.
However, its a new TC, not remanufactured. One year warranty on both.
Obviously these boxes cost less in the UK but I still need someone to fit it - and if I ship one down and it goes wrong, then....

The chap from Pau also said that if there is no noise accompanying the hesitation, then its the gearbox and not the TC....

@Datatek @Truffe @Volusia @sharkey964 @tombankes @blue beasty

rustynut said:

Update -
I have been onto the LR guy in Pau who wants 5200 euros to supply and fit rebuilt box and new heavy duty TC. Thats £ 3800 which sounds less than 5200 but is still quite a lot.
However, its a new TC, not remanufactured. One year warranty on both.
Obviously these boxes cost less in the UK but I still need someone to fit it - and if I ship one down and it goes wrong, then....

Click to expand...

There's a garage near Bellac, 'the English garage' they are very good and not over expensive. Their number I will find and pm you but I'm out in the motorhome at the moment, a friend was quoted around four grand to replace a Saab engine, they towed it from the French garage she had taken it to and the whole lot came to £750 fitted.

if you get a groan along with the rumble, plus the revs fluctuating by around 200-250rpm...TC is fecked....

Slipping gear shifts could be old oil and filter. low fluid level or the clutches slipping (hope not!)

Drain fluid, and check for condition...only fill with the correct fluid, use nothing else, plus a genuine filter and go from there...the quality of the old oil and filter will reveal if the box is getting tired.

It is the fact that the TC lockup lining is made of soft cheese that causes problems with these boxes. Bits come off it and contaminate the valve block. Caught early a new TC and flush out can do the trick. But more often than not eventually a new or recon box will be needed.

Gearbox finally gave up. Couldn't move. So am replacing the soft german cheese lined TC with a new Spanish hard cheese version or so I am told - and a fully overhauled gearbox. All work done by Toutain 4x4 in Pau.