This is a set of "GN1 ROLLER ROCKER ARMS" for a 1986 or 1987 Buick Grand National, T Type, Turbo T, or GNX 3.8 liter turbo V6. These are available in 1.55 or 1.60 ratios. They bolt to factory Iron heads, however they must be notched to clear. Taller valve covers are required for this set.
