Can anyone tell me the correct fluid for the diffs and capacity please for a supercharged 05

Assuming it's auto, then it's castrol saf-xo now replaced by castrol syntax

Front 0.61litres
Rear 1.1litres istr Bodsys Brake Bible
Software Updates Contact me
RRS Timed Heat/Remote kits - Contact me
BAS Engine Re-maps/ EGR Blank EuIII and EuIV
Clock On The Dash/ SNOTM /3Flash / BT Update /Service Reset/Error Codes read\ Gearbox Reset
See it HERE

If the rear is the locking one then it's 1.5L of Castrol SAF Carbon Mod Plus 2012 SDV6 - it's missing a couple of cylinders
2008 TDV8 - it was a labour of love and is much missed

Yes, didn't bother going into locking diff as there are so few Rrs with locking diff that it's unlikely he has it.
But you are right for locking diff.  Bodsys Brake Bible
Software Updates Contact me
RRS Timed Heat/Remote kits - Contact me
BAS Engine Re-maps/ EGR Blank EuIII and EuIV
Clock On The Dash/ SNOTM /3Flash / BT Update /Service Reset/Error Codes read\ Gearbox Reset
See it HERE

lol ok thanks but i better do a search to find out how to tell as just bought it .))

The only way, short of taking it off road in slippery conditions or in to a proper axle twister, is to look at the rear diff. Raise the vehicle to off road height and then look through the rear wheel arch under the body. You should see the EPB box and the rear diff. If you have a motor on the rear diff then it's the locking one. If no motor, it's the open diff. As Bodsy says, the likelihood is that you have the open diff.

See here for a photo of a locking diff as seen through the rear wheel arch:
http://www.disco3.co.uk/forum/topic91421.h...fferential 2012 SDV6 - it's missing a couple of cylinders
2008 TDV8 - it was a labour of love and is much missed

cheers .)