The Weaver model has the earlier fancy "pin striped" paint job on the engine/tender. Don't know the era you model, but later in life these engines had the basic dark green with just "Pennsylvania" on tender and the number on the cab.
Also, being a commuter engine, it has a small tender. May be a tight squeeze to get control system and sound system in the tender. The MTH G5s tenders always looked a little "tall" to me - maybe they did that to get all the electronics inside?
If I remember correctly, the LIRR G5s had a larger tender (similar to a K4s tender).
Found this picture in another post: Weaver G5