Seems G is the later revision for the diaphragm type DV. They then changed to another new part number which was the piston type, so D was released in piston form and the latest is now c.
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It goes in order
06F 145 710 A > B > C > G
Then VAG released the piston type (note the new part number)
06H 145 710 D.
The latest version is part no. 06H 145 710 C which is different to the D in that the outer cone is removed. This is what is fitted to TSi engines.
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Confusing!