The 1965-68 911T Cast Iron Distributor
This Bosch cast iron distributor has a black tag, 0231.159.001. And is used in the Porsche 1965 to 1968 911T model.
Bosch-0231.159.001-Advance-Curve
This 0231.159.001 is a supersession from the first 911 cast iron distributor, 0231.121.006. It can be a direct replacement in the earlier car as they have an identical ignition curve. The change from the 006 to the 001 is in the rotor. The 006 uses the 356 stepped shaft rotor and the 001 uses the 912 rotor with no step.

Changes to the 0213.159.001 Distributor
Some parts have become no longer available. Like the cap and condenser, so if you have a darker brown cap and a yellow wire coming out of your condenser, you have the original parts. It is hard to see the shaft change, but you will know when you try and fit a stepped rotor. You can recognize the 0231.159.001 distributor by the tag or the shaft if there is no tag.
Porsche Cross-Reference Number
Porsche does not use the Bosch number, 0231.159.001, but they have their own number, 901.602.021.CX. for the 6-cylinder Porsche 911T engine.