Frequently Asked Questions About Mack RD Truck Chrome Stacks & Tops

What size exhaust stacks fit my Mack RD model year?

Mack RD trucks from 1989-2004 typically use 5-inch diameter stacks, though some models came with 6-inch systems. Check your existing exhaust outlet diameter before ordering. RD688, RD690, and RD6 series all share the same stack mounting specifications. For trucks with factory mufflers, you'll need straight-cut stacks. For trucks with aftermarket mufflers, measure the outlet style (mitered or straight) to ensure proper fitment.

Will chrome stacks rust or discolor from heat?

Quality chrome stacks feature triple-plated chrome over steel construction that resists rust when properly maintained. However, the first 12-18 inches closest to the exhaust outlet will develop a golden-blue heat discoloration over time - this is normal and doesn't affect durability. To minimize corrosion, wipe down stacks weekly with chrome polish and avoid letting road salt sit on the surface. Stainless steel options are available if you prefer lower maintenance.

Do I need special brackets or modifications to install chrome stacks?

Most Mack RD trucks require stack clamps and possibly new mounting brackets, depending on your current setup. Factory exhaust systems often need a reducer or adapter to connect 5-inch stacks. Installation typically takes 2-3 hours and requires basic hand tools. Some drivers need to adjust or relocate air cleaner pipes for clearance. Curved stacks may require additional cab guard brackets for stability.

What's the difference between curved, straight, and miter-cut stack styles?

Straight stacks provide the classic vertical look and are easiest to install but may deposit soot on your cab in certain wind conditions. Curved stacks angle the exhaust away from the cab, reducing soot buildup but requiring more clearance space. Miter-cut tops direct exhaust at an angle and create a distinct sound. Bull hauler styles feature a longer curved section. Consider your typical routes and parking situations when choosing - curved stacks can be problematic in low-clearance areas.

How do chrome stack tops attach, and will they blow off?

Stack tops secure with either clamp-on bands or weld-on tabs, depending on the style. Clamp-on tops use stainless steel bands that tighten around the stack opening - these stay secure when properly installed but should be checked monthly. Weld-on tops provide permanent attachment but require professional installation. Wind-resistant designs like load king and turbo styles have internal baffles that prevent blow-off at highway speeds while still allowing proper exhaust flow.