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    Well, it is another common topic that comes up quite often is the differences in the shaker scoops for the Trans Am between the years.  The earlier years of shaker scoops from 1970 to 1976 are fairly similar. In the later years from 1977 to 1981 there are quite a few differences with the addition of available engines for the Trans Am.  When looking at the shakers, there are really two main parts to the scoop that determines what year and what engine the scoop will fit.  The main part is the shaker scoop itself which main style and shape helps determine what year it came from and is commonly made of a fiberglass or hard plastic.  The second is the shaker base which determines what engine it fits on and is made of metal and attached to the main shaker scoop by rivets.

 

     In the earlier years from 1970 to 1976, the scoops basically remained the same shape.  The scoops were rounded in the front and had gentle curves to it.  And since the only available engine combinations were the Pontiac 400 or the Pontiac 455 (in varying flavors such as HO and SD), 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.

     Now in 1977, things with the shaker scoops get a little bit trickier. 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.  1977 was also a one off year for the design of the scoop itself.  The scoop was only 2 inches tall and had a hard line ridge running down the center of the scoop.

 

     In 1978, the ridge down the center of the scoop disappeared and the scoop was heightened to 2 1/2 inches. 

 

     So the shaker scoop sat a little bit higher out of the hood in 1978 (shown on the right) compared to 1977 (shown on the left).

 

     Now, also in 1977 with the addition of the Olds 403 engine, 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.  The shaker scoops themselves from 1978 to 1981 were all the same on top with the exception of the 305 shaker.  The shaker for the Trans Ams with the 305 engine had a notch sticking out of the side of the scoop on the passenger side.  So you can easily tell a 305 shaker scoop from the rest by looking at the outside.

 

     For the rest of the shakers from 1978 to 1981, the top part of the shaker assemblies were all the same for the 301, the 403, and the 400, but it was the bases that were different.  The Pontiac 400 and the 301 shaker bases were all centered in the front middle of the shaker scoop.  The difference between these shaker bases were that the 400 (W72 and the L78) the base ring measured 16 1/2 inches and the 301 base rimg measured only 14" wide.  So, if you look at these two bases you can see that they are centered in the frontmiddle of the scoop.

  Now, if you compare that to the L80 Olds 403 base ring, it is offcenter of the shaker scoop to the front and to the left.  As you can see in the photos below how the base ring is offset to the front of the scoop and also off to the passenger side as well.  You can also usually see this from top and side angles as well.  You can also see from the side shot that the base ring of the L80 Olds 403 set-up that it is quite a bit taller than the 400 or 301 counterparts.

 

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