Superbird brake booster

[boss429kiwi]

Hi (New Zealand)

My original brake booster has blown (Superbird, 6 pack, 4 speed).
Since I am an impatient $&#%, I purchased a reproduction 70 b body booster from Year One, to find the firewall mounting studs were different. I then ordered a 69 b body booster thinking this was my next best option.
I was wrong, this stud pattern was different again.

I'm going to send my booster over to be rebuilt (should have done this in the first place!  )

But I need to ask, What brake booster is correct for a Superbird? And why so different to normal?

Thanks

[6bblgt]

all '70 b-body (non-HEMI) cars with power disc brakes had a Bendix dual-diaphragm brake booster with 5/16" studs on the firewall side

all '70 b-body HEMI cars with power disc brakes had a Bendix dual-diaphragm brake booster with 3/8" studs on the firewall side
 
the bolt pattern on the firewall side was also different between the two

[boss429kiwi]

What's with the different stud pattern, between the original and correct reproduction 70 booster.
I've seemed to have collected a graveyard of reproduction boosters, and nothing fits.