It's a Little Giant 2-MDQ-SC. ~550 gph @ 0 head, shut-off at 14.4 feet.
I've figured out that its most efficient at 250 gph, at which point the head is about 11 feet.
Picked it up at a flea market for $40...
I checked out the little giant website, and this is the closest I found to it:
2-MD-SC specs
I might try to swap some parts for the model 3, if I can get them cheap.