8T1387 Servo-Master Cylinder Seal Kit fits Caterpillar 621R 621S 631D 633 633B 633C

•  Fits Caterpillar Cylinders 
• #621R, 621S Servo-Master Cylinder#3G6904
• Serial#12Y1-UP;2TF1-UP 
• #631D Servo-Sender Cylinder#3G6904
• #631D Servo-Sender Cylinder#5J8606
• Serial#24W1-UP;66W1-UP;28W1-UP;29W1-UP;39W1-UP;68W1-UP
• #633, 633B, 633C Servo-Master Cylinder#5J8606
• Serial#66M693-UP;86H1-UP
• 3/4" Rod x 1-1/2" Bore 
• Includes U cup and Piston seals
• After market seal kit for Caterpillar equipment