Here's the full list of features for the Silverado 3WT and 4WT, including all the RPO codes. Thanks for finding and sharing the PDF @nebula1701

Font Parallel Number Event Rectangle
Font Parallel Rectangle Number Screenshot
Font Screenshot Number Parallel Document
Font Parallel Number Pattern
Font Rectangle Parallel Number Screenshot
Rectangle Font Parallel Screenshot Number
Font Rectangle Parallel Screenshot Number
Font Parallel Number Document
Font Parallel Rectangle Screenshot Number
Font Screenshot Number Document