Originally Posted by Losiho
I have literally just installed the Spec R BD5 gear diff in my MR-4TC BD. It fit without any mods. All I had to do was remove the metal washers on either side of the outdrives to fit inside the rear bulkheads. I'm using the standard driveshafts with the Spec R plastic drive shaft blades.
they arent called metal washers, there called spacing shims, they are 10mm. They should not affect the plastic blade fitting into the outdrive, they simply allow specific clearance for the differential in the bulkheads.
To answer the OP's question, the Yokomo gear diff works, you can shave a little material off the face of the plastic blade so it doesnt bind in the outdrive during suspension operation.
If it still binds, you will need shorter bones. You cant just boltup BD5 44mm bones onto your old BD axle. You will need the entire BD5 rear universal 44mm set and the BD5 rear hub carrier along with 5x10 ball bearings. It all bolts right up.