Master Cylinder with 4-3/4" High Reservoir

SKU: 10-487

Master Cylinder with 4-3/4" High Reservoir

SKU: 10-487


New Master Cylinder with 4-3/4" High Reservoir. It replaces our part numbers: 10589R / 10590R / 10596R - This reservoir is a universal unit that replaces Ford / IHC / Workhorse / Freightliner with 50.80 or 2" bore - Switches are included for both the casting and the reservoir - Either switch can be removed if not needed. Works with Hydromax brake booster. Also used with the RV Workhorse Chassis W22 and W24.

Measure reservoir height before ordering, this reservoir is 4-3/4" tall. Freightliner uses 2 different reservoir sizes. For a master cylinder with a short 3.5" tall reservoir, use part 10579.


  • Bore Diameter: 50.80mm or 2" (Bosch)
  • Reservoir Capacity: 84 Cubic Inches
  • Overall Reservoir Size: 4-3/4"H x 6-1/2"L x 5-1/4"W
  • Split: 50/50
  • Primary Outlet: 9/16-18
  • Secondary Outlet: 1/2-20

For a replacement Differential Pressure Switch that mounts on the casting order 36984.

For a replacement Reservoir Fluid Level Switch on the reservoir order 36-987

For a replacement Reservoir Cap order 10380 (does not include diaphragm)

For a replacement Diaphragm order 10381.

Differential Pressure Switch:
The differential pressure switch reacts to a loss of master cylinder hydraulic pressure in either side of the split hydraulic system and can illuminate a warning light at the instrument panel. When pressure is lost in either the primary or secondary circuit of the master cylinder, the switch closes. The electrical switch will remain closed until the malfunction is corrected. When both systems develop normal pressure, the switch will return to center and open the electrical switch circuit. A mechanically latched connector is attached to the switch. The switch has two tabs on a common terminal (positive) and is grounded through the master cylinder.

Fluid Level Switch:
When the fluid reaches a predetermined level (low fluid level), the switch closes and can illuminate a warning light at the instrument panel. A sealed and mechanically latched connector is attached. The switch has two terminals, positive and negative, which are interchangeable.

Vehicles Applications:

  • Chevrolet B7, 1993-2002
  • Chevrolet C4500 Kodiak, 2003-2009
  • Chevrolet C5500, 1992
  • Chevrolet C5500 Kodiak, 2003-2009
  • Chevrolet C60, 1991
  • Chevrolet C6500 Kodiak, 1990-2009
  • Chevrolet C70 Kodiak, 1992-1996
  • Chevrolet C7500 Kodiak, 1997-2009
  • Chevrolet T6500, 1996-2002; 2004-2009
  • Chevrolet T7500, 1997-2002; 2004-2009
  • Chevrolet W7, 1997-1999
  • GMC B7, 1993-2002
  • GMC C4500 Topkick, 2003-2009
  • GMC C5500 Topkick, 2003-2009
  • GMC C6000, 1990
  • GMC C6000 Topkick, 1990-1996
  • GMC C6500, 1992-1996
  • GMC C6500 Topkick, 1997-2009
  • GMC C7000 Topkick, 1992-1996
  • GMC C7500 Topkick, 1997-2009
  • GMC P6500, 1992-1996
  • GMC T6, 2001
  • GMC T6500, 1997-2002; 2004-2008,
  • GMC T7500, 1997-2002; 2004-2009
  • Isuzu FSR, 1996-2002
  • Isuzu FTR, 1996-2009
  • Isuzu FVR, 1997-2009
  • Isuzu HTR, 2005-2008
  • Isuzu HVR2, 005-2008
  • Workhorse Custom Chassis W24, 2004-2005; 2007-2009
  • Workhorse W24, 2004-2009
  • Workhorse W25, 2005-2009

Tech Specs

OEM/Other Numbers:
  • MC391540
  • M630276
  • W8005118

Estimated Shipping Dimensions: 9" x 9" x 5"

Weight: 12.56 lbs

Mill Supply has been the #1 supplier of step van parts for over 30 years. If you have a Workhorse, Utilimaster, Grumman, Morgan Olson, Supreme, International or other type of walk-in van you have landed on the right page. You will not find a more complete listing of parts for stepvans anywhere! With research and development on-the-go, new products are constantly being added to keep up with the growing industry. You can count on great customer service, fast shipping, and discount prices when you shop with us. It doesn't matter if you use your truck on-the-job, for deliveries, or run a food truck, you can count on Mill Supply to keep your vehicle in top shape. We distrubute parts for Todco, Whiting, Velvac, and Kason. If you have any questions don't hesitate to either contact us via email or give us a call at 800-888-5072 between 8:00 a.m. - 5:00 p.m. E.S.T. and one of our experienced representatives will be happy to help you.



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