Welcome to the forum. Condolences on your loss.
As for the D22, yes, several changes late 2001.
The good news is that the engine drivetrain is bomb proof (actually most have been exported to Africa where reliability is appreciated)
So the wings definitely changed post facelift, it seems likely the fuel tank did too as the fuel system was different.
In terms of parts, tricky in the UK. Pick ups didn't have many sales back then in the UK and almost no sales in Europe, and as above most have now been exported.
eBay can be useful for second hand parts. MilnerOffRoad have some parts new. Plenty available in Australia, but import is challenging.