The basic info on this loco is available on Lionel's website -
But - there is one for sale on eBay right now. Based on the (apparently catalogue) photo on the auction, this loco does appear to have the over-extended firebox, and is too "lanky" in general for a PRR K4, which was a somewhat chunky-looking loco.
(You could add a more-proportionate 4-wheel trailing truck and have the only PRR Hudson...but that might cause the entire 3RO world to implode. Just kidding. It's a shame that Lionel decided to resurrect that old long-as-a-Mountain tooling, especially as they had/have the better K-Line tooling available - I think.)