PRJ
From Just Solve the File Format Problem
{{FormatInfo
|subcat=3D and CAD/CAM Models
|released=Presumably 1990
|extensions=.prj
|pronom=[https://www.nationalarchives.gov.uk/PRONOM/fmt/1831}
fmt/1831}
] PRJ is the 3D Studio (DOS) project-file format.[1][2]
File Information
PRJ files begin with the 2 byte hex values 3DC2