This pump has helical gears and will mount to the lower drivers side of an LT1/SBC (not sure about LS1 but it will likely fit) 1 pressure stage, 5 scavenge. Scavenge is an open manifold and should create 22-23in of vacuum on most motors. This pump is upwards near $2000 new. The one on the right is for sale (this is my spare) but I don't need to hold onto it and need the money.

$450