IIRC, The Despatch No.9 was an ex- US Army 86 foot long steel hulled tug-- quite a number were built during WW2, a a number ended up in other's hands later on. This makes the model about 1/77 scale or so....
Despatch No.9 was a Standard Oil Company tug, based in the San Fran area. Somewhere along the way, Lindberg lost the association of the name with the model, but the stack still comes with the large "S" molded on.
As JTilley pointed out, the Diesel tug is the old Pyro mold. The other tug you're building is smaller, about 10 inches LOA compared to the Diesle tug's 13.5 inches. I think this was a Lindberg original-- I don't recall ever seeing it in anyone else's box. In some of the old versions, it was sold as a motorized kit. This little tug seems to be a generic harbor tug-- I don't know of any specific prototype it was modeled after.
I always found it ironic that Lindberg released the little tug in a box as "Coast Guard tug", when the Diesel tug was the one that was legitmately in the USCG. I built my Diesel tug as the USCGC Messenger-- she was stationed at the USCG Yard in Curtis Bay MD. (There's a picture of Messenger in Dr Scheina's USCG Cutters and Craft book.) I could find no evidence a tug like the little one was ever a USCG vessel.
I agree with your comments about the thick plastic. When I built my tug as an RC model, I replaced some of the heavy palstic parts (decks, cabin parts) with much thinner sheet plastic, to reduce topside weight and improve stability.
In any case, your work looks terrific.
-Bill