OK here's the latest.

There are four different software platforms depending on which model year of vehicle, and the solution to changing ratio's is different for each one.

X308/X100 AJ26 engine - needs a custom-written PCM program
X308/X100 AJ27 engine - needs a custom-written PCM program, but it's different to AJ26
X350/X202/X103 (up to 2005MY) - needs a modification to the VID block
X356/X206/X150/X250 (2006MY onward) - needs a modification to the CCF

The AJ26 is still a work in progress
The AJ27 is tested
The X350/X202/X103 is tested (VID)
The X356/X206/X150/X250 is also tested (CCF)

The 2006MY onward cars are the easiest to change.

In all cases an IDS/SDD is needed to make the changes.

I've had to put the ratio-swap in my car on the backburner because of other projects and my day-job. I'll get around to it sooner or later.

Thanks!

Interestingly, I've never seen the X356 designation anywhere else but on this subject. Makes sense, just didn't know about it.

My notes show X356 is XJ 2006-7, uses VID. IDS/SDD has/had/uses/used X356VIDBlock.xml

There are some XJ MY VINs in the Vehicle Spec file but I'm not sure exactly which range.

Cambo can probably post more.

Post more what?

If you hook up an X356 (an X350 from VIN G49701 to H18679) or an X358 (from VIN H18680 to H32732) to SDD it presents you with a CCF...

That'll probably do - I couldn't find the VIN range quickly.

So writing to the VID failed?

Excellent news!

So no luck on the AJ26 yet? I'm finally bought a VCM Rotunda of my own. (waiting on the shipment)

Now you need to find a legit version of IDS or SDD software.