Replacement Rear Calipers for Audi 100, 1990, Base Model

[Einhorn Hofmann]

Took my car to the Audi/VW independent garage last Monday, telling them
that the rear calipers needed to be replaced.  I left it there all week,
expecting that would be enough time to confirm the problem, source the
parts, and get it fixed.  We spoke on Thursday and they told me the car
would be ready the next day.

When I go there on Friday, I was surprised that all they'd done was taken
the wheels off and confirmed that it needed new rear calipers.   He
explained that at this vintage, getting the parts is a bit of a hunt that
they sometimes need to conduct over a prolonged period.

When I mentioned that I'd sourced the A/C parts and he confirmed that he
could do the A/C rebuild, he asked a comment that if I could also find a
pair of rear calipers while I'm at it, they'd be happy to install them
also.  But he cautioned that I'd have to be careful to get the "right
ones", because of all the variations in models and submodels.

I looked my car up for year, model, engine, etc, on CarID, and it showed a
number of different looking rear brake calipers (loaded and unloaded) for
the same base (non-quattro) model,  Going online, a site like CARID lists
at least 5 different variations that fit my model.  For
example,they've got multiple
manufacturers including "Cardone", "Centric", and "World Brake". Prices
range from under 50, to closer to 100, unloaded.  When I select one of
them, it give me the sub option "with ATE" vs "with Girling" original
calipers. I think I can make out "Girling" under the rust in the one's I've
got installed right now.

Any suggestions for getting the right parts, such as a site that matches
the parts to the VIN? I'm in Canada, but happy to order from the USA since
they have a much larger supplier base.  I just don't want to get the wrong
ones, which would waste a trip to the mechanic, and in addition cause the
tedious problem of trying to return parts cross-border.

Thanks for any ideas,

MC