difference between 66 & 67 intake manifolds

Does anyone have some quick guidelines (or even photos or link to images) about what the differences are between the 66 and 67 4bbl intakes?
Much appreciated!

In case anyone else is looking for this info... here you go:

The 4 bbl intakes casting numbers are as follows

1965 9778816
1966 9782896
1967 9782896
1967 9786286
1968 9790140
1968.5 1974234
1969 all were aluminium
1970 9799068