It's so frustrating dealing with any story that comes out of the Big News industry. They have the resources to come up with more information than does the average schmuck but usually just provide so very little.
I should add to my above post that the body should also have some rank insignia on it which should also help pin him down.
Most of the WWII flights will have some paper trail listing everyone aboard but sometimes you've got the extra unrecorded passenger.
Following the assumption that he's from the AT-7 crash---and not a different one--- I went to Joe Baugher's amazing website and tried to find the serial number/info with an AT-7 search but evidently Joe didn't have anything on this one
The article from the Sac Bee referred to to the Modesto Bee article of the period. About 1948 They found a engine number. They claim to have also recovered the entire crew or what was left of them. These people were sight seeing. We tend to view people of this era as primitive however they were anything but. The officer from the lab reported no paperwork with this person. For this person to be from the crash, he would have gone missing from Mather for ever without anyone noticing. He would have also exited the plane leaving the rest of the crew to be converted. I think we should wait for the lab to ID him. They are not willing to commit to any line today.