From 7/76; w/ 4" Front Raised Height
From 7/76; w/ 2 1/2" Front Raised Height; 1976 1/2 - 1986 Blazer or Jimmy and short bed pickups with a 4"suspension system will require a transfer case lowering kit part number RS6631. Some vehicles equipped with 2 1/2" suspension system may experience a driveline vibr; Block Kit No. RS70054 is required with RS86209 Rear Spring for a 4" lift.
This is a summary only, please use Does it fit my vehicle to check if Rancho RS6631 can be installed on your vehicle.