I belive the reason for not using a flywheel lock and using a
pulley counterholder was the design of the crank itself.
If I can remember way back to late 96 when I got trained,
the modular (112 V-6 / 113 V-8) use offset or split journal
crankshaft throws. If you looked at them from the side, they look
like two offset O's, or like half an Audi logo. If the flywheel were
to be locked, and 400ftlbs of torque applied to the main crank bolt, the crank shaft could twist or even snap. Seen it done
before. The flywheel lock should only be used when loosening
the flywheel bolts.
That is why the main balancer counterholder tool is soo important.

The torque spec for these is 200nm plus a 95 deg torque angle.
A cheater pipe for the counterholder helps hold it against the frame or body. I use a 24" Snap-On breaker bar to do the job
of loosening and angle of torque.

The flywheel lock still works fine for all older 102,103,104,111,119
120 motors.

Work with care
DR.D