By modular if we are talking 4.6 and 5.4 in 2 valve and 3 valve setups I will say in a word....crap. ( just my opinion )

Ford had from ( and i will be generous ) from 2000 to 2010 to do something productive with these engines and all the 5.4 is...in my opinion is an anchor. Won't go into the 4.6L because it came out in 92 in a 4V version that Ford didn't put into the Mustang GT.....

They had the right idea years ago with the 5.4 DOHC in the Cobra R. The technology was there....reference the 5.0L we have today...but why Ford didn't pursue the DOHC V8 in "mass" production still boogles me.

As for longevity...sure they last long...with the piston slap...cam phasers....and so on. Just sayin' owned 2 5.4 2V's and I currrently have a 10 5.4L that sounds like a rattle trap....