Anybody know if my car has one and if so, where do I get one?

1981 CADILLAC FLEETWOOD BROUGHAM 6.0L 368cid V8 MFI (9) : Exhaust : Exhaust Manifold Heat Riser

Item Price Core Total
ATP Part # 105013 {Heat Risers}
* Non-stock item--shipping delayed up to 2 business days

$64.79

From rockauto.com

http://i40.photobucket.com/albums/e202/jayoldschool/exhaustriser.jpg

Anybody know what this actually does and do I need it in the car? Also this is for a fleetwood, does this matter?

When the engine is cold, it blocks off one exhaust manifold, causing the engine to heat up faster. It then opens when the car is warm. Do you drive your car in cold weather?

does it really block off one side? wouldnt that choke the engine?

Well, I live in WA so I would say yes. But is it a must to have?

No, it's not a "must have". However, the car will run better with it.

No, it won't "choke" the engine. The exhaust will run back up through the crossover in the intake manifold to heat it and the intake charge while the engine warms up. Then, it will open when the car is warm allowing full exhaust flow.