try giving matt humphris a ring. he sells gripper clutch lsd for i think £700-800.
the one he sent me by default had the clutch on both sides of diff but lack of space meant i couldn't fit the speedo drive
but specify to him if ya need to use the stock speedo cos he later requested gripper to build me a version with the clutch on only one side so that i could fit the speedo gear. blog post #943
it's normally a 2-way 45/45 ramp but ask matt if ya wanna different ramp cos gripper can change the ramps free excluding postage within few months of purchase