Freight engines were painted Dark Green Locomotive Enamel (aka Brunswick Green), as were diesel passenger engines (E7, PA1, and I think E8 models) until about 1948 or '49. Most steamers were also painted green, the exceptions being certain K4's. There were also a few diesel switchers painted Tuscan for passenger switiching operations in Sunnyside Yard on Long Island. Pictures of these can be found in the various Morning Sun books. (I'd look up specific pics in the PDY
books, but my PRR books are currently on loan to a friend.)
The change from small lettering (with no keystones on cabin cars, and "ball keystones" on freight cars) took place in 1954. Microscale makes sets for both schemes, as did Champ and Middle Division.
By single and triple lines, I presume you're talking about the stripes on passenger cars. I can't remember the exact year the Pennsy changed that, but I believe it was '48 or '49. Before that was the multiple-stripe, two-tone-red "Fleet of Modernism" scheme on some cars instead of the "normal" Pennsy scheme. Also, don't forget that Pennsy went from using gold leaf to Dulux gold lettering and stripes as a cost-cutting measure in approximately 1952.
The PRRH&TS used to put out an excellent book that was nothing but information about PRR passenger equipment, including cars that were used in joint service with other railroads. They also produced a wonderful volume that included line drawings for various freight and passenger schemes, including the dates they were used. I don't know if these books are still available. You may want to check their website to see.
I hope that helps you some.