They are Vitaloni Californias and yes, the base is separate from the mirror itself. The base mounts to the car and the mirror pivots on a long threaded bolt inside the arm. Be careful when you drill and mount them as they are a very small view angle and if you position it wrong, you will see very little from them. The also make a convex version for the RH side. Pegasus racing sells them along with many other online shops. If you wish, you can sand down the exterior surface which has a texture to it and body color paint match them. That was a Gary Hall trick.
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