As I mentioned in a previous blog post, I got lucky and came across a whole bunch of vintage, produced-in-1973 Synthane Taylor boards.  The production date codes were 1973, as verified by the still unopened bags they were in:

Pretty amazing that these had sat unused all these years.  And as mentioned, they bear the same little ‘Tc’ marks on the PCB substrate that the originals do (albeit different colour):

Previously I had posted that I thought these were the marks of Techniques, the company that produced the original kit boards back in 1974.  I have since determined that Tc actually stands for Taylorclad.  Techniques, I believe, did not make the substrate or blank copper clad stock that was ultimately used for the kit boards – they were just contracted to lay them out, etch, tin and package them for buyers.

In other blog posts I’ve mentioned my disappointment, as someone who desires a replica that is as close to original as possible, with modern PCB stock.  It just doesn’t look right, which is obvious in photos.  Again, compare an original Mark-8 board (right) to one I produced on modern copper clad stock (left):

It might not be immediately obvious to the untrained eye, but it’s definitely something I notice.  So I’m grateful these boards have been available.  The fact that they are only 0.030″ thick vs. the standard thickness of 0.060″ actually works to my advantage; I can simply make one side of the two sides, then the other, on two separate sheets, and then bond them together….