Originally Posted by spock505

Hello Stretch, hope all is well in 190 world, can I tap you for some advice please.

My S124 project car is now back on the road having never really had a proper chance to drive under normal conditions. Some background, 126k miles with four speed (722.4) auto OM606.910 oil burner.

Unfortunately it has a whine between 35 - 60mph after which it seems to get a lot quieter. At first I though it may have been the center bearing so changed that for a minor improvement, also changed the front wheel bearings which again afforded some improvement but still very noticeable.

Oil was drained and refilled before putting back on the road however it does leak or seep out some oil, seals?

My only check has been getting under the car to check play on both exit flanges, there's a fair knock perhaps around 2-3mm of play at each end.

So I have decided to replace it or have the unit reconditioned by a diff specialist.

There’s a good supply of used diffs but only one with exact matching numbers but the price is high £400 + with post as is the miles. This is almost the cost of a full rebuild. Other vendors have said the numbers (the ones in your earlier post cast onto the rear cover) don’t really matter, it’s the ratio that important.

Being a ‘glass is half full’ type of person I am naturally keen to believe this, however I do have one or two reservations. So my questions is

a) did you find out what the numbers stand for ..and
b) which if any are not relevant ?

For example, I have been offered a diff with very similar number but mine has ‘30’ as opposed to ‘25’’

Number on diff back plate:

R124 351 30 08 ratio 3.07

Diff for sale

R124 351 25 08 ratio 3.07

One suggestion is to measure the points between the flanges, this I have not tried as yet but might be tricky getting an accurate reading due to the diff part obstructing straight line measurement.

Sorry for windy post but I am going around in circles.

Thanks