Are

TKR5140/TKR5141 (Differential Gear Set (internal gears only)/Differential Cross Pins (6pcs))

and

TKR5150/TKR5149 (Differential Gear Set (6pcs, requires TKR5149 pins)/Differential Cross Pins (6pcs, requires TKR5150 gears))

fully interchangable both ways?

Is it recommended to replace the differential case (TKR5113 (Tekno RC Differential Case)) when replacing the gear set and cross pins?

/Birger