msd distributor

Really closed unit?
I just purchased a new MSD pro billet last week for my drag car.
I had to remove the vacuum unit and install the mechanical advance.
Came with the distributor.
This was the only way I could get a mechanical advanced MSD distributor.

http://static.summitracing.com/global/images/instructions/msd-8534_frm29056.pdf


I wanted the the Mopar one but $369 seemed a bit steep for me.