My ABC's

[dingo151]

I'm picking this project up midstream so I'm having to work backwards on a few things. I've got a 96 block bored .30 over and it' s suppose to be decked but I won't know for sure until I get the crank back from the shop! Anyway on the side of the block and stamped into RH side of the motor there are letters by each cylinder. C,C,D,D,D,E front to rear and I'm wondering if these could be ring sizes. I don't have an accurate enough instrument to discern any difference in the bores so I'm spit-balling here. Anyone else have an idea?

Thanks
Dean