From my 2002 Mopar Performance catalog..
Looks like the only difference is the cam and intake.
Cams
300hp 250/264D 335/401"L
380hp 288/292D 501/513"L
My understanding is that R/T heads never came on the crate motors.
They stopped selling them when the heads ran out.
A friend on mine was partner for KRC Performance, they were actually buying the crate engines and stripping the R/T heads off.
I saw the advertisement myself several years ago.
Edit: Just off the phone with Bill from KRC and he confirmed it.