Thanks, Mike.
I'm not asking out of interest in a new truck - I'm asking out of interest for how long they'll support the 6.4 Hemi by building new trucks. If they keep building for a while, I stand a chance of repair for mine if something goes deep six.
If they stop building 6.4, it's time to look for something else. I don't need to be left stranded by a questionable engine, no matter how "low" the lifter failure rate is. Add to that the 66RFE transmission.
They will support the engine for many years to come.
I had a Ford F-250 with the 7.3L diesel. They stopped production of that engine in early 2003 and it is still supported today (even though it was only in production for about 4 years in the USA). There's still a lot of OEM parts for it and a solid aftermarket presence.
Talking with the Ford parts department guys as it was becoming more and more obsolete (minimal common parts with newer engines and longer out of production). They told me that the original parts suppliers for the production line are usually 3-5 year contracts. After that Ford would go through another couple of contract for OEM parts through other companies to OEM specs. Around the 15 year point lower volume parts would not be continued and would be relegated to stock on hand until they were gone then the part would be officially "discontinued".
The reason part numbers change (usually up by one number or letter) is for a revision in the part or a supplier change.
Long story short the 6.4L will be supported for a long time by RAM and longer by the aftermarket since so many were built. The 7.3L still has a large aftermarket even though it was only in production for less than half a decade.