Actually only made these, the 2.3l version, for 11 years, its the Mazda L engine series, first used in 2001 until 2012
Ford calls it a Duratec, its a name Ford uses on a few engines, some it makes, some are made by other companies, like the Mazda L engine, but Ford owned 33% of Mazda back in late 1990s, so 1/3 of the engine is a Ford, lol.

Yes, Ford requested the intake runners and heated thermostats be added to the Ranger version of these engine, 2001 to 2003, bad ideas, in 2004 they were back to standard Mazda L engine

But yes to make production, and assembly, less costly press fit is becoming more popular.
Key ways cost more to machine into BOTH the shaft and gear.
And in the old days the tolerances were NOT that great, so you HAD TO have keys to make sure parts stayed in sync, lol.
With computer machining you get a very tight fit

I don't see the failure rate on these engines being that high, or the cause of the failure, if there is one, to be the press fit timing parts
Admittedly the press fit is not ideal for DIY repairs, but doable.

 

Ron, so are the other "duratec" engines used in fwd cars even close to the 2.3 we know and love? I think there is a 1.8 and 2.0 "duratec" I always assumed they were just short stroked versions of the 2.3. And I was pretty sure one of those engines has been in a Taurus or something before 01 which is why I thought the duratec has been around for 20+ years.

 

Read here for Duratec "name": https://en.wikipedia.org/wiki/Ford_Duratec_engine


And here for specifics on Mazda L engines: https://en.wikipedia.org/wiki/Mazda_L_engine

2.3l for FWD cars was 23EW model
2.3l for Ranger was 23NS model

They are the same engine internally, different cams, and 2001-2003 Ford add-ons to the 23NS