just get a sunny master cylinder,they're 13/16's & set up for front disc's.or a 260z master cylinder,which is what i have,which is 7/8th's.really,all you need is to go to a competent brake place & tell them what size you want for the master cylinder,they should be able to tell you what to buy.to use the datsun m/c's in a lancer booster,you probably have to do some machining work.the outside diameter of the datsun part is slightly too big for the front of the mitsubishi part.a friend of mine machined down the m/c,but now id get the mitsubishi bit made to suit the m/c.the part i'm referring to is the alloy casting which bolts to the front of the booster,& that the m/c bolts onto.