Does anyone know anything about these gearboxes or know anyone who can sort mine out.  

In all 3 forward gears it pulls well.  

Put it in reverse and it slips loads, almost so that I cannot get it in the drive without a run-up at it.  It has had a recent gearbox oil change and new filter.

Chris, are you sure you have a TH400 in your van ??
I thought your van was a fairly modern one which I'd expect to see a 4 speed trans in.....??

Did you change the oil and filter because of the slippage problem or did it start after the filter service....??
If you changed the oil yourself what was it like and was there much sludge or debris or sparkly bits in the pan..??

Assuming that the oil level is correct and that the filter is fitted OK, not too many things can cause the reverse gear to lose drive without at least partially losing drive in forward also since the reverse uses many of the elements for forward.
The most likely is a bad brake band and the next is a sticking/ malfunctioning valve spool.

The valve spool can sometimes be sorted out with the box still in the vehicle but the band is non adjustable on TH400's so the box has to come out. If it's out and you have to delve inside for the band, you may as well replace the other "soft parts" of the gearbox since they are most likely to be close to the end of their useful life.

Locally there are a couple of autobox specialists. Personally, I suggest talking to John at Poole Autos in Parkstone (yes, he's a friend but he definitely knows his boxes and he'll see you OK).
Alternatively, there's a fellow (pete) on the Nuffield or another outfit over t'other side of town.

Thanks for that Tel .....

Definately a 3 speed box
Changed oil because of slippage, and the oil was dark when it came out but no sparkly bits.

Will try the auto box people and see what happens.

Thanks.

OK matey. No worries.
Let me know how you get on, eh??.................

no luck with prop then mooooosh??

Prop????

Quoted from DOUBLE TROUBLE

no luck with prop then mooooosh??

  Nope ade did not get back to me yet.

Quoted from raindance

Prop????

  Mmmmmm I have another gearbox that was rebuilt only 1000 miles ago. The prop on my vanis what I would describe as having a real UJ attached to the end of the gear box .... the other gearbox has a UJ that has 4 bolts and U shaped clips that hold it onto the back of the gear box.



This is the picture of the "end" of the gearbox and the propshaft.

I dont know what to do now .... getting quotes all about £1000 to have the box reconditioned, and there is this rebuilt one on my doorstep!

Two possibilities spring to mind, Chris.
Assuming the rebuilt box is a TH400:
You can make changes to your existing prop to accomodate the other gearbox......
.......or better, if you have another rebuilt box, you can get the gearbox people to swap your old tailshaft and tailshaft housing onto the rebuilt box. Should be much cheaper than a rebuild but it does depend on whether you already have this other box or whether you'll have to part with some dosh to get it.....

Quote, by the way, are often similar as many places use the same book to price jobs.........

Cash often can influence the price.