When did Chrysler stop using the 340 mold for the 360??? Ive read 71 was the only year, then I also have seen 70-73 360s where cast using the 340 mold witch would equal thicker cylinder walls, any input would be great Thanks!

73 the last year, when they stopped making 340s. Casting numbers are what you look at.

So they used the 340 mold for the 360 up to 73?

I think the only way to be sure is to sonic check.

Up to and including. The early casting number is 3418496 IIRC. Might have shown up in some '74s too. Sonic check is a good idea on any of the older stuff.

Sonic test it. I have a 74 360 block that is thicker than my 71 340 block. Same shop, same tester, same day.

If it's the early block, that would be correct due to the smaller bore.