We have a 1989 190e and we want a spare transmission for it in case the one in this car goes out. I found a good deal on a 190d 5 speed with flywheel and I'd like to pick it up. I want to be able to resurface the flywheel and bolt in this trans with a new clutch in the event the current transmission needs to be rebuilt. Before I drive out to it though I'd like to make sure there is nothing I am missing. I understand the ratios are different but other than first they're not that different and would make a good spare.

Based on this Mercedes manual transmissions | Mercedes-Benz turbo it looks like it should be fine.

EDIT: If anyone is wondering this trans has started to grind the 1-2 shift and I'm sure its only a matter of time since this car only sees track use.

The 190d flywheel is single mass, your 2.6 has a dualmass. The transmissions input shaft is specific to single mass or dual mass, you can't mix and match. Also your 2.6 has 3 built in timing Windows which the 190d lacks. You would have to add the timing Windows to the single mass flywheel in order to make it work. I would save the money and use it toward replacing the syncros in your 5spd.

Single mass has long input shaft, dual mass is short.
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Ah good info. I thought all the 190's had a single mass and w124 got the dual mass though. If they are different will they mount to the crank the same?

The reason we want this spare is that it is cheap and we don't want the downtime rebuilding the transmission will create. We are going to run this in a few endurance races which is a tight season with work and if it happens to fail in a race we aren't going to be rebuilding anything in the pits. If this transmission gets significantly worse and we have time to rebuild it we will.

Also our 190 is an 89 if that makes any difference.

If the transmission in your 2.6 is the 717430 or 717435 you'll be able to use the transmission from the 190D with the flywheel from the 2.6 all you need to do is swap the yokes on the transmission. But if the transmission in the 2.6 is the 717433 has a dual mass flywheel you won't be able to use the transmission from the 190D unless you buy a single mass flywheel for the 103 engine

Is that a year change or will I need to find the part number on the transmission?

The best way is to find your transmission part number the older cars used the single mass flywheel you might have a single mass flywheel Mercedes stared using dual mass flywheels I think it was in 1990 or 1989 I'm not sure. I don't think you'll be able to use the 190 transmission is a weaker transmission made foe a 4 cylinder engine with less torque I'm using a 717410 in my E300D for the last 3 years but my engine is stock and I don't race this engine