Spindle Assembly / Cub Cadet 918-06978.  Pulley is part number 756-05038.
Pack Size:1
Replaces:

• MTD 918-06978, MTD 618-06978, Cub Cadet 918-06978, Cub Cadet 618-06978
• SNAPPER 771373

Fits/Specs:
Cub Cadet RZT-L54, L54KH, L54KW, S54, S54KH, S54KW, XT1-GT54, ST54 and XT2-GX54 with 54" deck; MTD 13A7A1ZW099, 1417A3ZW099, 14A7A3ZW099, 17ARCACW099, CGT5426, CSLT5424, ZT-L54 and ZT-S54 with 54" deck
Thread: 5/8 "-18 UNF, Height: 6 1/2 ", Packaging Type: Branded box, OD of Pulley: 5 7/16 "

SR-5 (P)