I recently grabbed these manifolds on sale and am confused what year / application they may have been for. I have read conflicting information on the part number and years, and the head-to-manifold flange bolt count, for those years. Hope that makes sense.
It appears they are RA3 GTO manifolds from 1969 (per Wallace on the RA / HO manifold descriptor sections). See below and attached pic.
http://www.wallaceracing.com/exhaust1.htm
.............but then it also shows the same part number used in 1970 on the broader Wallace listing. See below.
http://www.wallaceracing.com/exhaust.htm
I have also read the 3-bolt head flange was only utilized in 1970.
So, are they 1970 GTO RA3 manifolds?