intake manifolds

how can I ID the different intake manifolds?
as I have noticed some are a different width

thanks

If you go the the Buicks.net shop, you will find a pretty good list of casting numbers. There is even a version suitable for printing on both side of one paper to take to swap meets!

I am going from memory ,but should be close.
Distance between bolt holes
322 8 3/8
364 8 7/8
401-425 9 1/8

thanks folks

the old guy has come through
the manifolds are aftermarket
so there is no casting nos

thanks
rocky