Shimano offers adapters for IS 2000 and Post Mount calipers that are compatible with Shimano disc brakes.
The Shimano disc adapter for the front brake with an IS 2000 caliper, designed for fitting a 180 mm brake disc to a Post Mount 74/6 fork.
The Shimano disc adapter for the front brake with an IS 2000 caliper, designed for fitting a 203 mm brake disc to a Post Mount 74/6 fork.
The Shimano SM MA F203 PP front wheel disc adapter for Post Mount calipers to Post Mount 6/74 and 203 mm discs
The Shimano SM MA F180 PP front wheel disc adapter for Post Mount calipers on Post Mount 6/74 and 180 mm discs.
Shimano disc brake adapter, flat-mount caliper, rear wheel mount for 160 mm discs, including bolts