I do not think it is a TP22 but could be wrong. We thought it may have been a TP220 base with an additional heat sink attached to it, then decided it was not, but take a look and see what you think.
Here is an image:
And another view
Sean Patrick Small
I have 80 SL's in my house, and I know this thread is older. I am almost positive that the screws on the top of the socket, that go through the porcelain are fused somehow with the heat sink at the base. I say this because when you spend your 75 USD to buy it, it comes with the...