Chrysler R and D Gen 4 Heads

[ViperC]

I happened to come across some heads that are listed as Chrysler R&D Gen 4 Heads. They have some obvious differences: header bolt location, rocker stands are flat, intake port is almost flat to the head, etc to the production heads. Does anyone have any information on heads like these? They look like a cross between a Gen 3 and Gen 4 head, which would make sense if it was in R&D. IMG_3472.jpgIMG_3473.jpgIMG_3467.jpg