All depends on what series truck you have. If you have a 1 1/2 ton "4000" series truck(4100, or 4400) it came standard with a 216 "Thriftmaster" engine, with a 235 "Loadmaster" being optional. If your truck is a 2 ton "5000" series (5100, 5400,or 5700), or "6000" series(6100, 6400, or 6500) the 235 "Loadmaster" was standard, with no other engine available until 1954, when the 261 was an option for the "5000", & "6000" series trucks.