This is the Hydraulic Hose Tension Track on a Century 300 Express Series, EB4 Express, and Challenger 4300 Express by Miller Industries. See Brochures for part schematics and Features for related parts and to see what models this will fit.
Related Parts:
Main Boom (12-0804262)
Hose Tension Spring (12-0303521)
Hose Tension Pulley (12-0703484)
Hose Tension Track Cover (12-0713937)
Fits:
Century Express 300 Series (03/1998 - Current)
Century EB4 Express (03/1999 to Current)
Challenger Express 4300 Series (03/1998 - Current)