N15/G15 used steel crankcase shields. The P11 used alloy. Same mounting hardware. Will probably require some modification for spring and side stand clearance.
N15/G15 shield 02-6334
P11 shield 03-3086
clips 02-6491 (2 req)
bolts 04-2265 (2 req)
washers 000011 (2 req)
nuts 000004 (2 req)
Mike at Walridge Motors usually has a few in stock