One of the attractive possibilities in this context might be a tank destroyer. In World War II, it was initially U.S. doctrine that tanks need not be able to take on other tanks, but would only assist infantry in breaking through enemy lines. The job of confronting enemy tanks was assigned to a vehicle called a tank destroyer, which mounted a much larger gun. The American tank destroyers did well during the war, but by war’s end, the doctrine was abandoned in favor of up-gunned and up-armored tanks.
If you find this topic interesting, there are lots of publications that go into it thoroughly. George Forty’s book about the M4 Sherman also goes into tank doctrine and tank variants built on the Sherman hull, such as tank destroyers (M4 Sherman, Blandford Press, New York, 1987). Two more good sources are Fighting Tanks, by Ian Hogg ( Grosset & Dunlap, 1977), and Sherman: A History of the American Medium Tank, by R.P. Hunnicutt (Presidio Press, 1978), along with several of the Vanguard paperback accounts of U.S. tanks in World War II and Korea.
I have an HO-scale model of a tank destroyer, not the most common World War II version, which was the M10, but probably the late-war M36, also used in Korea (I express uncertainty because the model is unlabeled). These had more powerful guns than did gun tanks, 90-mm high-velocity guns, and open fighting compartments instead of turrets, so that the bigger gun could be accommodated. The photo below, from Forty’s book, shows an overhead view of the M36 turret, though mounted here on an M18 chassis, not the modified M4 chassis used for production M36 vehicles.
The length of the 90-mm gun is striking in this view.
Shown below is the model I have, which obviously lacks the muzzle brake seen above but otherwise has a fighting compartment much like the prototype photo. I may try and make a muzzle brake, as they are so obvious on many (but not all) photos of the prototype.
Here is that same model vehicle, paired with a Sherman, on my Roco flat car. The tank destroyers weighed somewhere in the vicinity of the weight of an M4 Sherman, so these two vehicles are well within the 100-ton capacity of the flat car.
Note above that both vehicles are loaded with guns facing forward. This was the most common practice in this era, though photos exist of tanks shipped with turrets turned to the rear.
These kinds of armor loads are, as I have mentioned previously, appropriate for SP’s Coast Line because of the presence of Camp Roberts, home of the 7th Armored Division in my modeling era. Here is another example of a waybill I might use, a U.S. Government waybill since this is government property:
This bill, which happens to have been filled out with a Teletype type face, reflects a movement from what was the primary Army armor training center in 1953, Fort Irwin, near Barstow, California, to Camp Roberts.
Armor loads allow some indication of the recent (for my layout) Korean War and training in its aftermath, and in addition are suitable for my layout’s locale on SP’s Coast Line.