If anyone else cares to try this...

My son and I just converted his 1995 Jetta's rear brakes from drum to
disk after he blew a rear wheel cylinder seal this afternoon.  We had
another Jetta with rear disk brakes in the driveway that he hadn't
finished stripping for parts.  Doing this conversion was planned,
actually, but we...um...advanced the plan a bit, rather than buy a wheel
cylinder.

The stub axles and caliper mount all fit the existing suspension, which
was a pleasant surprise because it avoided changing the rear suspension
and realigning it.  With a bit of careful re-forming the brake lines fit
as well.  The front/rear brake proportioning seemed fine to us after the
conversion with the existing rear brake pressure valve; i.e., the fronts
lock first but they all lock up.  The parking brake cables must be
changed because the ends are different.  The caliper hose mounts snap on
from the bottom--don't try to remove them from the top or you will
probably break one of the tabs off.

Pretty straightforward and easy overall.  Anyone with rear drums could
do this easily with junkyard parts.  Stub axle, axle seal protector,
splash guard, caliper mount, caliper, brake hose, hub and rotor (with
wheel bearings, thrust washer, castle cover, and cotter pin), and brake
cable are needed on each side.  About 1/2l of brake fluid sufficed to
fill and bleed the system afterward (the rear lines, of course, were
completely empty).

Oh...and my son reports that the car stops much better.

JRE