The question has several possible answers. If the check is paid payable to the estate-then the PR would have to distribute the proceeds to the named heirs in will after expenses are paid.
It is possible to petition the court to have proceeds distributed in PI cases to spouse and heirs directly.
His son would be entitled to automobiles if he was the only child and could accomplish this at the DMV without probate as exempt property. He then could transfer the automobile to you.
This would not be possible if the deceased had other children without 100% consent.
The best bet would be to have a probate attorney guide him throught the process with at least a consult.