Just had a reply from Forge about the updated gearboxes:
We don’t know the date of change or from which VIN number I’m afraid, but it affects all the VAG 6 speed units, not just the GTI, so S3, TT etc. If it helps, all those with the new casting also have the new TSI engine.
So I wouldn't have thought any ED30s would have the new TSi engine as the uprated engine (230bhp) was based on 2006/07 engine and can't see VW updating it towards the end of the ED30 run. Will try and find out more on this. I'm sure there was a TSi thread on here a while back.
Hmmmm - sommat don't quite sound right. Forge are talking a little bull!

When VW "update" any major component, such as engine, transmission, or rear diff, they give it a new three letter prefix. Just like the original GTI engine was AAX, but the later ones were/are BWA - but it is still classed as the "06F" engine.
The DSG is another example - it is known as "02E", but has 20 different three letter codes for the front wheel drive boxes, and three different for the 4wd boxes.
If Forge state that these boxes are all mated to the latest chain-drive TSI engines, then they should also know the 3-letter transmission code. If they can't, get them to give me a VIN, and I'll find it!
