Here is a prime example of manufacturers sharing.

The Redline Maxitork with Speco markings.

maxitork.jpg

I can't 100% exactly say what went down with John Cain's switch to the newer 2bbl Holden 6 Manifold design but the casting improved substantially. This seams to tie in with the involvement of Hardiman.
Which down the line saw Terry Hardiman ending up buying and producing at least some of the Cain designs with Redline badging (and with this the casting improved dramatically). The prime examples being the 253/308 tunnel ram and the 4bbl Holden 6cyl manifold.