that's the same Piguet base, but more heavily modified. The Automatic mechanism has been removed and replaced with the RdM on the back. Some of the bridges are reshaped to handle this. Alliance Horologere (a wiki of watch info) hasa great video of 1151 reassembly (optically identical to the 1150). About 7 min in, when the barrels are in place but no rotor yet, you can really see the similarities in the barrel-bridge and overall layout
hiro.alliancehorlogere.com
A