I had a 68 with a 396 and I think the 409's were in the earlier trucks. The 71 and 72 had 402 big blocks which were .030 over 396 blocks. I have wondered if a glitch in casting or boring led to these engines. The short story is all these trucks had a bb option so it should fit. The 409 truck block with the taller deck height is sought after by hot rodders.


Evan