I've done a search on this and I'm now more confused than before

The story is
The 4.0 gems engine in the P38 is in need of a rebuild or replacement
But I had a 4.6 Thor engine in the shed that I kept for the discovery 2 in case that went on me but it's been good
So is it just a matter of swopping over the inlet manifold or is there more to it I believe the crank sensors are different is this a problem ?

The PCD of the drillings for the pickup in the flywheel is different, and the pickup carrier is different to suit, otherwise the engines are basically the same lump.

You could buy the pickup carrier, I bought one for mine, but I don't know if they are still available.

My engine is a GEMS short motor that is fitted into my D2. Apart from modifying the pickup carrier, everything else was the same, but check the bell housing dowel hole sizes, I seem to remember that we had an issue with them.

The THOR adapter part number is EIQ100020, still available and even one on ebay. I'll check the GEMS part number tonight. EDIT: ERR3693 looks like the one.

Peter