The 2-10-4 acquired the designation "Texas type" because the Texas & Pacific was the first railroad to use this new "Super-Power" design from Lima Locomotive Works. Lima delivered the first ten in class I-1, for which No. 600 posed for this builder's photo, in 1925 and repeat orders soon followed until by the end of the decade the line rostered 70 of these heavy-hauling oil burners. They had 63-inch drivers, 29x32-inch cylinders, and 255 p.s.i. of boiler pressure. With a locomotive weight of 448,000 pounds, they exerted a tractive effort of 84,600 pounds with a booster adding 13,300 pounds for starting heavy trains. For other specifications see the commentary for No. 603 following.