The D154 breaks down to:
D = April
15 = 15th day
4 = 1954
If you look up by the fuel pump there should be a casting number.
I've got an early 261 out of a 55 1st farm truck that I couldn't find the cast number at first. Like Dave states look by the fuel pump, in front of the pump in the depresion between the oil pan flange and the horizontal raise cast rib in the block above it. Had to dig to find it on mine as it was well cover 55 years of ancient grease. Has high mount water pump, no thermostat by-pass, only a by-pass oil filter and very few drilled holes on the sides of the block when compaired to the '59 261 I've also got sitting waiting for something to happen. The '55 the correct 'B' but the '59 has a 235 'B'. Rochester 'B' carbs are just like Dave, pre '68!
