During the early post-war years, the RSR did, without doubt, apply a sort of "mix and match" design method, of which the 433F was a typical product. The cylinders and running gear were derived from those of the 434B 2-8-4T of 1939 and the boiler belonged to the same series as that which would be fitted to the 423D 4-8-0 in 1954. The RSR management, evidently wary of a design policy that they saw as facile, authorised only one engine. What Rodnivacek thought of this is not on record. Once delivered, the 433F was put through its paces and was found to be a sound design after all. Before the tests were finished, however, the class 423E 4-8-4Ts, which were a tank version of the 423D, began to arrive from Krupp and it immediately became clear that two types of eight-coupled tank engine were not required. Although the 433F showed a more even starting torque than the 423E, owing to its three-cylinder drive, and had equally good running qualities, thanks to its Krauss-Helmholtz carrying axles, the motive power policy in force at Akohniçe at that time virtually guaranteed that the 423E would prevail. The solitary 433F remained in service, sharing the duties of her victorious rivals, until 1978.