Help decoding my intake manifold

[my124677n]

Based on the GM code of 3927184, (per many web & decoding sites) this should be for a '69 small block 350. However the casting is June 11, 1968 and it has the hole in the front of the manifold for the oil tube. Was this code used in 1968 as well? Thanks in advance.

[1968RSZ28]

Read this CRG thread...  http://www.camaros.org/forum/index.php?topic=807.0

Paul

[my124677n]

Thanks.