Rotary 13089. Bad Boy 037-6015-00 / 037-6015-50 Spindle Assembly (short). Old style cast iron housing. 

*below is a breakdown of this spindle assembly

Qty            P/N                     Description
2                037-6009-00       Bearing Retainer Ring
1                037-6017-00       Spindle Housing
2                037-6023-00       Bearing
1                037-6019-00       Short Shaft
1                037-6018-00       Long Shaft (not included)
2                037-6021-00       Small Bearing Spacer
2                037-6020-00       Large Bearing Spacer
1                037-6022-00       Shaft Retainer Ring

SR-2(P)