On my late production '76 (3947 of 4100), noticed that the front strut lock nuts were finished off with a black varnish like substance where the threads exit the nut and the lock tab was brushed with what looks like white paint. My car has the original struts. I imagine evidence will have been removed with repairs, restorations, or maintenance.

I didn't think much about it until I saw it on a MY75 car (2nd picture). Haven't noticed it on anything earlier. What's on yours?

Also, anybody know why the strut shaft has the internal thread?

Look at the pix of Steve G's pristine 21k mile `73 2L's front struts in the O&H Forum's "The Few, the rare...." nailed topic in about 3rd page of posts.

It's the same type of reference marking, which was used much as similar paint on appliance & electronic case screws to verify non-tampering during warranty period.

That is one fine example of a well preserved 914.

Thanks for pulling the reference, so quickly, out of your obviously well organized cranial catalog.

Internal thread is so you can put a long bolt or cut off throttle cable end to pull the hydraulic shock up into the strut bearing. Not needed on gas shocks since they extend all the way up.