I have a 1988 5.7 L that needed new exhaust shutters. I ordered the A3 version, and it did not fit well into my Y pipe. When I forced the shutter ring flush with the end of the Y pipe, the short axis was squeezed, and this squeezing prevented the shutters from moving freely - they were stuck half open and half closed. I took a sharp knife and trimmed some of the rubber away from the pinch points close to the hinge, and then they worked without getting stuck in the half closed position. The plastic ring still did not fit right in the Y pipe opening, so I just laid it on top and slid the rubber tuber back up onto the elbow. My guess is some y pipe castings are not quality controlled with respect to the thickness and shape at the end of the Y pipe, so some A3 shutters may fit better than others depending on the thickness of the Y pipe.
So far so good after two outings. Will report back when I check them next summer.
Jim
