trains during the day and freight trains at night. There were different classes among the New Haven units noting some differences between the manufacture of each batch. Initially, they were simply listed in two groups in the Summary of Equipment, with #0700–#0709 listed separately (with a different weight and tractive effort) than the remaining DL-109 locomotives. The 9-30-1945 Summary of Equipment designates four different classes: DER-1 (Diesel-Electric Road) units #0700–#0709 had the original design with a mass of vents on the roof, DER-1b (#0710–#0719) were nearly identical, with square winterization hatches over the roof fan housings (which were also applied to the original units following the winter of 1941), DER-1b (#0720–#0729) and DER-1c (#0730–#0759) all had simplified rooflines, and other minor variations in appearance. The classes would remain the same until the start of an extensive rebuilding program. In the 6-30-1949 Summary of Equipment the class designations were adjusted into three classes: DER-1a (#0700–#0709), DER-1b (#0710–#0749) and DER-1c (#0750–#0759). The class was rebuilt from 1949 to 1951, replacing the plywood sides, removing the decorative side windows in favor of a steel screen, and several other changes, with only #0740 retaining its original appearance after being rebuilt. Two DL-109s received a special rebuild c1953 to make them able to "MU" (multiple unit) with more than one other unit; originally, they only had the MU cables on the rear, meaning that only a back-to-back pair could be made. The two special units had cables put on the front so they could be used to make a 3-unit set for longer trains. #0727 had the nose rebuilt with an access door, raising the headlight and changing the contour of the nose. In the Winter of 1953 to 1954 New Haven A-A-A units #0720-0722 with #0721 in the lead could be seen in far northern Maine on the Bangor and Aroostook Railroad, helping haul massive tonnage of potatoes, usually in the now-famous red white and blue "State of Maine" products reefers. These were leased by The BAR. The DL-109s eventually ran their last miles in the late 1950s in local commuter service around Boston. One special unit was retained through the 1960s in Boston as a power plant; #0716 was converted in late 1958 to produce power for a test third rail in Boston, only having a single 539T prime mover. Eventually #PP716 became the last DL-109 on the face of the earth and