Dennis,
Here is a video of my 2 Legacy K4s coming out of the yard double headed. The first K4 is #1330 a standard post war model that Lionel had in the 2012 catalog. I purchased this one from a forum member off the buy/sell forum. The 2nd K4 #3880 started life as a Polar K4. If you look real close at the builders plates it says "Polar RR #25". The one crazy thing about the Polar K4 was when I blew the whistle the steam smoke came out of the dome sideways, Lionel did not include a whistle shield used by the PRR so the steam would blow straight up and not blind the engineer. Don't know why they excluded a .25c part but it bugged me so I purchased a whistle shield made by Precision Scale and glued it to the boiler. Works just like #1330. The Legacy K4s are hard to find but well worth the trouble as the smoke, sound and operations are top notch and worth the effort. Oh by the way the Legacy K4 and the Kline K4 are both identical less the Legacy electronics. The Kline K4 #1361 handled 031 and 048 curves with no problem. I would thing the Lionel K4 would do as well. I never ran them on my home layout only at the club so I am just guessing.
JohnB
