The 3120 may not be much shorter then your previous rig, depending upon how you arrived at your 37'4" length. At least on my 2015 model Montana states that they measure from the center of the kingpin to the rear of the bumper. That's all well and good, but the kingpin is about a foot and a half rearward of the nose. On a Legacy model the rear ladder protrudes 6 or 7 inches rearward of the bumper. My 3100rl is listed at something like 35'3" or so, but in actuality it's a little over 37' long. Don't understand why they can't do as I did and drop a plum bob at each extremity for an accurate measurement.
2015 3100RL legacy...2005 Ford F-250 CC SB. Tows like a charm! 4/19 Updated to 2017 Chevy 3500 CC SB SRW -hope it tows as well as my F 250 did!