Long shot but I'm after info on 2.4 Utd ten valve / 2.4 jtdm twenty valve component interchangeability.
For example is the 20 valve bottom end the same as the 10 valve?

To the best of my knowledge, the 1.9TD and the 2.4 TD had little more than a new head and injection system, the block remained the same, AFAIK even the multijet shares the same block, with very little (if none) modification from the TD days. The Wikipedia JTD page seems to agree with me on this one. If i were you though, I would take a look at some of the Alpha or Lancia forums, the FIAT 2.4JTDs are as rare as hens teeth, and finding anyone here with that level of knowledge is going to be tricky, where as, on the other hand, many of the Aphas have them.

Thanks
I've checked on eper and the part numbers are different for the Alfa 20 valve and fiat 10 valve.
I have a marea 2.4 ten valve and also an Alfa 159 2.4jtdm although visual inspection of both engines is almost impossible with ancillaries fitted in the engine bays.
The 20 valve engines are hugely expensive to find used (eBay)
My Marea is the 130bhp
The ten valve alfas got 140bhp
The 156 20 valves had 175bhp
And my 159 20 valve has 200bhp.

I'd love to feel how that engine would perform in the marea being almost 400kg lighter.

I'd love a 159 sw