Yes. We have one other diesel locomotive, the diminutive D-1 which is a tiny Davenport diesel hydraulic. It's essentially a 1930's dump truck in a miniature locomotive carbody and frame, and a somewhat tricky beast to operate.
The "heavy" power will continue to be the 50-ton Baldwin electric (#300) seen behind #150, but the new diesel should be able to tackle much of what we use 300 for, and be able to enter many areas 300 can't go (either due to track curvature, or lack of trolley wire.
150 will also allow 300 (which turns 100 this year!) to get some badly needed downtime for overhaul. Also, while 150 will be well cared for (several departments are eager to see it arrive), it will be a work engine and not accessioned into the museum's collection as it is outside our scope as a museum of mass transit vehicles. It will be used to support track maintenance (work trains), moving heavy rolling stock (especially subway/elevated cars and heavy interurbans), and can be a rescue/tow unit in the event of a power outage.
Wondering if I'll see the Western Route double-tracking finished before I retire...
Photo: Melbourne W7 No. 1019 on Route 78, Bridge & Church Streets, Richmond, Victoria. 10/21/2010