Many people that bought the 380 would have been happier with the 300/320. Both motors made a little more than that to comfortably advertise the HP rating.
Neat motors with reliable stock replacement roller lifters.
The 380 had a sorta choppy cam to get that HP with only 9:1 compression and low lift with stamped rockers. At some point the 380 magnums got R/T cast iron heads and possibly roller rockers.
And many 380hp crate buyers didn’t have the basic tuning skills and/or had expectations of new magnum truck starting up on a cold morning.
