Am I correct in remembering you (or somebody else) also stated they never carried bombs AND rockets during WW2?
For the reasons mentioned. The only way to lug bombs is on the wing hardpoints, so it means no DTs. As the rockets were used over Japan, they needed the DTs to get there to shoot em.
They did carry both in Korea. Interesting to note that they carried 6 when they had DTs and 4 when they carried 500 pounders. Apparently this was standard practice.
And in the interest of 51 rocket fairness I dug through all the 51 books I have, and there are many. There was this shot of a CBI P51D with the rocket tubes and DTS.

And the RAF ground attack Mustang IIIs in the MTO carried up to 8 Tiffie style rockets, although this meant no bombs or DTs.

