Factory Workshop Manual Torque Specs
 

All of my torque wrenches are in Newton-meters because that's the Porsche, Toyota and VW standard.

But now I have a grey binder set of 72-83 manuals and every torque spec is given in mkp and ft-lbs. The dates at the bottom of these torque spec pages are in the mid 70s.

I have a red binder 912E workshop manual and the torque specs are only in Nm. Written in 1975 and not revised.
My friend has a red binder 944 set and the torque specs are all in Nm. Written in the early 80s and not sure about revisions.

Are all 72-83 sets in mkp and ft-lbs or did they just change the units and not consider it a revision when they printed my set probably 20 years ago?

The specs are easily converted....

yes, but I'm asking if there was some point where they changed from Nm to ft-lbs.

The manuals may have been tailored for the country for which they were written.
They'd never bother to revise them just to switch measurement standards, they'd go nuts.
Revisions were made to fix or update, not for unit conversions.
The metric or SI standard is pretty much worldwide except for a lot (if not most) English speaking countries where they use English units.
In the 60's or early 70's there was talk of the US switching to metric to comply with the SI standard, but it never took hold.

The 912E was built only for the US market but the workshop manual only uses Nm.