ABS Sensors for 164L

["Dan Nicholes" <drnicholes@domain.elided>]

I am a first-time contributor to the list and I would appreciate any help 
that the readers can provide.

About 3 months ago, my shop (an authorized Alfa repair station which shall
remain nameless) changed the rear shock absorbers on my 1991 164L with about
85,000 miles.  On my drive home, the ABS light came on.  I returned the car
to the shop immediately.  They explained that the ABS sensors had been
destroyed when changing the shocks and that these are commonly replaced when
the shocks are changed.  They ordered the sensors -- they say I need 4 --
but to date they have not arrived.  They are back-ordered to Italy.

Question 1:  Is the replacement of the ABS sensor an expected part of
replacing the rear shocks or did the mechanic not take care in removing
them?

Question 2:  Why do I need 4 for 2 wheels?

Question 3:  Shouldn't these be available from some other source? Like from
whoever makes the ABS? If so, does anyone have the part number?

Question 4:  Is the replacement of these sensors a big deal for a checkbook
mechanic like me? -- or something I should leave to the pros?

Any help will be appreciated.

Dan Nicholes
1967 Duetto
1991 164L

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