does everyone get the aftermarket bell housing installed on the th400's?
It looks to me like the older turbo 400's are missing the very top bolt on the bell housing to bolt up to the LS1 block. just curious if people run without that bolt or not.

 

I run a TH350 with stock bellhousing and I only used 5 bolts skipping the top bolt.

 

Its not missing, it never had the bolt hole-5 work fine
Some 4L80E's don't have that hole either
Guys swap the BH if they want an SFI approved one, or have a BOP 400 and want to convert it to a Chevy pattern

 

I am missing one on my LQ4-TH400, and you cannot drill/tap it either as its a coolant passage right behind it.