The Dodge Challenger Message Board

I just figured out that my '73 340 was originally a 318 car from the VIN. Now I peered around my motor and found some casting #'s.
2780930-340-5 0583 - drivers side
6*23*67 - passenger side

I assume by the second one that it is a date, now is that date specifically for when that motor was made?

Casting dates are from when the block was actually cast. They were done in batches and most production cars came with a block cast a month or so before the car was assembled.

But the 340 was a new engine for the 1968 model year. So they probably had a lot cast early on to get production of the engine sorted out. It would have been installed in an early '68 model year car. Probaby sometime in July/August/Sept '67.

2780930-340-

CID: 340
YEAR: 1968-73
FAMILY: LA

Look of the front of the block for another set of stamped numbers. They are right below the driver's side head surface. Those numbers include the date the engine was assembled.

It is not uncommon for a block to be cast several months in advance.