Does anybody know what the numbers and letters mean on top of the cam caps on a cossie.

To cut a long story short i've just snapped number 3 on the exhaust side i know that they are line bored and you should'nt use anyh from a different engine, but needs must.

The one that snapped was a letter V and the spare one that i have is a letter X does this mean that this spare one i have is bigger or is there no size at all.

Or has anybody got any ideas for me on what the best way to get around this with out changing the head.