Rubber mounts flex under torque and let the engine move, which shows up as driveline slop and header contact. Polyurethane is stiffer and does not collapse the way a soft rubber puck does, so the engine stays where it was set. This is the red insert, and it drops into the clamshell housing.

Hooker 71221015HKR BlackHeart Polyurethane Engine Mount Insert Features:

• Fits GM Small Block Chevy applications using the common 2292 style aftermarket mount.
• Polyurethane construction resists the flex and collapse of a rubber mount.
• Red.
• Designed to work with the Hooker BlackHeart clamshell engine mount housing, part number 71221004HKR.
• Sold individually.