That's an AEB025 pressure sensor, so is the later (and latest) type. Difficult to see the attaching wiring, if the wiring doesn't look tampered with and there is no adaptor (to adapt from old type AEB013 connector on old type wiring loom to AEB025 type connector, i.e. a short bit of wire with a plug on each end) then I would suspect you have an N type ECU (so is slave / much more common type similar to even the latest type systems). If that's the case then, as explained above, the V6 software is very likely to work with it. Even systems fitted 11 years ago are unlikely to be pre-N type. One way to confirm would be to check your petrol fuel trims while running on gas - if fuel trims (when running on gas) don't drift to one extreme or the other then it will almost certainly be N type, if your fuel trims do drift to one extreme (rich or lean) when running on gas then this doesn't prove that you have pre-N type because this could also be explained by there being a problem with your LPG system or with how it is calibrated. Yet another way to check is by looking on the back of the LPG ECU, if it is N type it will be stamped AEB2568, I suspect yours will have a B or C suffix at the end of that board code too (still implying N type).
Simon