Having a hard time decifering block number!

It's in a 64 Valiant. Supposed to be a 64-65 273 ci 180 hp engine. The distributor isn't right, I can't find the right rotor for it (that's in my last post), but all other parts I've purchased so far are correct for a 64 - 273 (water pump, timing chain set manifold gaskets etc.)
I got the block number from under the the front of the left side head, it's:
VX2 - 38904C
Can anybody decipher this? I can't find it on any of the Mopar or performance sites I've visited, not even close.
Thanks again, Wally