Thanks for the input! It was the fender and grillwork above it that made me think Diamond T. Even though there is "USA" on the crane cab, there are no other markings and I don't think this vehicle is in US military service. A Coleman G-55 crane truck was also in use at the test site, and that particular vehicle, in Army service, carried a full compliment of stars. I think Richards posting might be the case as to what the type is. I believe it was owned by the Eichleay Engineering group of Pittsburgh who had been contracted to do some heavy equipment movement at the test site as Eichleay had a reputation for moving oversized items (penstocks for the recently built Hoover Dam is an example) and collected equipment acquired to perform such jobs.