Trans Am 400 with Shaker.
In the earlier years from 1970 to 1976, the shaker scoops basically remained the same shape. The scoops were rounded in the front
and had gentle curves. Since the only available engine combinations were the Pontiac 400 or the Pontiac 455, the shaker base was relatively the same.
From 1970 until 1972, the scoop also had a functional "flap" at the rear opening of the scoop that was activated by the throttle
and opened and closed depending on how much throttle was applied.
In 1977, Pontiac finally made a change to the shape of the shaker scoop. It was more streamlined and hard harder edges on it compared to the rounded
style of the 1976 and earlier shaker scoops. Also in 1977, the bases of the shaker scoops also changed to accommodate the differences
in the size and offset of the engines. So, the shaker scoops for the years 1978 to 1981 all had the same style when looking at the scoops from the top,
but the bases attached to the bottom of the shakers is what changed. There were basically 4 different configurations for the shaker
scoop bases from 1978 to 1981. There was the 400 base, the 403 base, the 301 base, and the 305 base.