So the mystery unit in question is the 2024 (nee 2058) that safely arrived at the Berkshire Scenic Railway Museum late Wednesday evening. This was a collaborative effort with Webb Rail LLC, the owner of former NYC "Babbling Brook", an obs car originally assigned to the New England States. Webb Rail underwrote the purchase and BSRM will store, maintain and interpret. The 2024 was chosen due to its sound mechanical condition (deemed best of all the units) as well as it being the second to last New Haven unit produced, in addition to the second to last F-unit built by EMD.
The BSRM is thrilled as this marks not only the return of the first New Haven locomotive on the property but the first time this type of unit called the Berkshires home since the late 60s (?) I'm hoping those in the know on this forum can help corroborate this question. We are also excited in that by the end of the month 2024 will be joined by NH 42 "Firestone", also no stranger to the Berkshire Line, helping to fulfill the organization's master plan of more authentic New Haven rolling stock. Currently, 3884, our wooden baggage car acquired from the RMNE, is the only piece with New Haven provenance.
As for the Hancock question, the ones currently on our B&M RDC were FRA tested and passed. This was only after a full rebuild by the Mechanical Department. Expect, at the very least, the 42 to have these.