From Team Associated:
The new caged thrust bearing set for ball differentials is a precise and easy-to-use upgrade for Team Associated ball differentials. The caged thrust bearing simplifies assembly, automatically spacing the thrust balls for equal loading. The thrust balls run on two V-grooved thrust rings for minimal drag.
#91990 is a direct replacement for #6573 diff thrust washers and #6574 5/64″ balls.
In addition, customers can buy a #91992 complete ball differential kit with caged thrust and #91991 ball differential rebuild with caged thrust bearing. These two new parts are direct replacements for #91702 and #7677, respectively.
Fits B6.3D, B6.2D, B6.1D, B6D, and older ball differential models.
#91990 – Caged Thrust Bearing Set, for ball differentials – $7.99 MSRP
#91991 – RC10B6 Ball Differential Rebuild Kit with Caged Thrust Bearing – $22.99 MSRP
#91992 – RC10B6 Ball Differential Kit with Caged Thrust Bearing – $67.99 MSRP