OK, from my experience with non automotive casting houses, no one keeps track of mold revisions. They do add -# to distinguish which mold was used to cast a part. Also, it's my understanding that what most of us call casting numbers are actually engineering numbers. Below are some pictures of three 340 blocks. All are cast between October 1970 to June 1971. Notice there's a -2, -6 and -8.
![IMG_20240626_181216631_HDR.jpg IMG_20240626_181216631_HDR.jpg](https://www.forebodiesonly.com/forum/attachments/img_20240626_181216631_hdr-jpg.126028/)
![IMG_20240626_181059070.jpg IMG_20240626_181059070.jpg](https://www.forebodiesonly.com/forum/attachments/img_20240626_181059070-jpg.126029/)
![IMG_20240626_181125985.jpg IMG_20240626_181125985.jpg](https://www.forebodiesonly.com/forum/attachments/img_20240626_181125985-jpg.126030/)
![IMG_20240626_181254150.jpg IMG_20240626_181254150.jpg](https://www.forebodiesonly.com/forum/attachments/img_20240626_181254150-jpg.126031/)
![IMG_20240626_175850097_HDR.jpg IMG_20240626_175850097_HDR.jpg](https://www.forebodiesonly.com/forum/attachments/img_20240626_175850097_hdr-jpg.126032/)
![IMG_20240626_181151891.jpg IMG_20240626_181151891.jpg](https://www.forebodiesonly.com/forum/attachments/img_20240626_181151891-jpg.126033/)
![IMG_20240626_175751939.jpg IMG_20240626_175751939.jpg](https://www.forebodiesonly.com/forum/attachments/img_20240626_175751939-jpg.126034/)