I have a 1981 trans am are the air cleaner same on all small blocks . i 305 motor?

No, the air cleaner assembly wasn't necessarily the same on all 1981 Pontiac Trans Am small-block (305) engines. While many shared similar designs, variations existed depending on the specific options and emission equipment installed on the car. Factors like the carburetor type (Rochester Quadrajet, for example, had different air cleaner bases), emission control systems, and even optional performance packages could lead to different air cleaner setups.

To be certain you have the correct air cleaner, you need to:

1. Identify your carburetor: This is the most important factor. The air cleaner base is designed to fit the specific carburetor.

2. Check your original air cleaner (if you have it): This is the easiest way to confirm the correct type.

3. Check your parts catalog: A 1981 Pontiac Trans Am parts catalog (either a paper copy or an online version) will list the correct air cleaner assembly based on your car's Vehicle Identification Number (VIN). The VIN will specify options and engine codes.

Simply knowing it's a 305 isn't sufficient to guarantee air cleaner compatibility across all 1981 Trans Ams.