The back of a rig sits low once the front gets a lift, and a rear block is the plain way to even it out. These cast iron blocks come as a pair, so you pick the height and pin size that match your spring setup and install both sides.
MPN 015-2 (1.5in / 9/16 Pin)
MPN 016-2 (1.5in / 5/8 Pin)
MPN 020-2 (2in / 9/16 Pin)
MPN 021-2 (2in / 11/16 Pin)
MPN 023-2 (2in / Flat)
MPN 025-2 (2.5in / 9/16 Pin)
MPN 026-2 (2.5in / 5/8 Pin)
MPN 035-2 (3in / 9/16 Pin)
MPN 036-2 (3in / 5/8 Pin)
MPN 038-2 (3in / Flat)
MPN 045-2 (4in / 9/16 Pin)
MPN 046-2 (4in / 5/8 Pin)
MPN 048-2 (4in / Flat)
MPN 055-2 (5in / 9/16 Pin)
MPN 056-2 (5in / 5/8 Pin)
MPN 058-2 (5in / Flat)
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