[loki_the_glt]

The early 244DL/245DL (up to 1979/80) had solid front discs; all others had ventilated front discs with necessarily thicker front calipers.

Although the mountings are identical the calipers are not interchangeable.

If the original poster's calipers are both 4-piston then it is possible that the upper one is for a 240 - some cars had ATE brakes at one end or the other although every 240 I've worked on had AP-Lockheed (Girling) calipers all-round.

The 900-series cars used sliding-calipers up front as, it would appear, did the 700-series cars so neither caliper is suitable for one of these cars.