I can't answer your question about the Durametric, but here's a look at which side is bank 1
https://sites.google.com/site/mikefocke2/what-side-is-bank-1
In a 986 (mid-engine), bank 1 is the 'passenger side' (Right) of the engine. In a 996 (rear-engine) the engine is placed backwards and bank 1 is on the driver (left) side.
See the potential for error?
(Lets not talk about RHD cars)