i use 4,
on each corner intake runner.
then attach my load leveler.
makes things super easy.

 

OK, will do. Super easy is what I'm after.

 

OK,

I used four, also.

I made a bracket for the front/driver-side out of angle. I just used one manifold bolt (using the stock bolt which came with the engine), and it seemed to work fine.

As a side note: 2-ton Performance Tools lift with a Neiko 8-ton ram worked fine (using the 2-ton arm extension setting)

 

those bolt holes are from international. they are where the air compressor mounts on an air brake truck. also very useful for the idi turbo motors to hold the air filter housing...

 

Thanks. I have come to the conclusion the holes are used for several purposes in various trucks and vans.