Rear Calipers-Wrong Pistons

[donohue@azstarnet.com (Terry Donohue)]

Finally decided to replace the rear calipers (Girling) on my '90 200TQ for
the usual reason-no parking brake.  After some calls to determine that new
ones were $420 each, I ordered a rebuilt pair from Blaufergnugen at $110
each.  Got them two weeks ago, but careful inspection showed they weren't
identical mirror image parts.  There were slight differences in boss sizes,
bleed screws, method for retracting piston, etc.  Then, I notice the number
cast on the side-the left one was a 38, the right caliper a 36.  Yes, my
car came with 38mm rear calipers; 36mm must be found on some other model.
I called Blauf, explained the situation carefully, and got the replacement
part in today to find that it is, once again, a 36.  They appear to package
all rebuilt calipers by side, without regard to size.  Simple math shows if
I end up using this mismatched pair, the braking forces will be off by 11%,
causing pulling on heavy braking.  Do I have to put up with this
compromise?  Can I somehow explain to Blau that this is an unacceptable
problem?  Or should I go somewhere else for my rebuilt calipers?
Incidentally, I got the new rotors for this job from Linda/Carlsen.  They
were the wrong ones, too, but Linda handled this very swiftly by getting me
the proper ones by the next morning!

Terry
'90 200TQ (2.0 bar)