Do a search on Water Pump 124. Many results. One thread states that this is a "Bear" of a job, book time 6 hours.

I have not done this job, but know that there is a Snap-on extension with
flexible 13mm? socket, that speeds the job.

There will be disagreement on this, but when I had a new pump put on my '92
124, I went with the Factory pump. Did this because of the 1 year warranty issue and the possibility that aftermarket design might not equal factory performance.

I had a pump done on my previous, '90 124. On this car, they had to also
do the Belt Tensioner.

Steve