Inlet manifolds

[DavidNLonsdale@aol.com]

Hi,
 
A few questions about inlet manifolds:
 
1.  Does anyone know the difference between AEC862 (100-6)  and AEC957 (3000)?
2.  How is the heatshield mounted on a BN4/BN7? Is it sandwiched  between two 
thin insulation blocks, or is the shield hard up against either  the manifold 
or the carbs with just one thick block?
3.  What is the thickness of the block or blocks?
 
I am doing a mod to fit 2" carbs instead of HD6s.
 
My thanks in advance for the answers.  

Regards,

David Lonsdale
Cirencester,  UK