So has the production line in Germany come to a standstill because of a lack of this part - of course not.
I would be having a right go at the dealer, the sales department has probably got exactly what you want fitted to a new vehicle parked right outside - cannibalise it.
the maoster:
We’ve currently got a 64 plate Actros off the road with a clutch problem. It has 50k km on the clock, Merc have said that they can’t get a part until July! Wtf?
That’s severe, will Merc provide a free hired unit till it’s fixed ? Doesn’t sound like a problem we’ve had with ours, surprised to hear we have some more new ones on order I was hoping they would get something different but alas no. 
All of ours come through Gullivers BB, all that Nobbies do in this scenario is stop paying for the vehicle from the minute it goes off the road! It then becomes Gullivers headache.
Ours are brought but never seem to see a hired unit when one of them is off the road for a while.
We had a merc actros only 6 month old that needed a new Ad-Blue sensor, merc said it would be about 12 week until they could get one! 
our gaffer told the local merc dealer to bodge it up so it would still work untill the part came. Also the previous model Actros on our fleet were having major problems of knocking itself out of gear when in traffic or approaching roundabouts and even when setting off from them and then unable to select gear.
Our gaffer had some new mercs on order and gave the back word on them due to Merc saying there was no problem with the gearboxes even though it was happening to every Actros on our fleet plus the appalling aftercare from the dealer. Suprise, suprise only a couple of week after this Merc have recalled the Actros for new clutch plates and kits fitting admitting there is a fault with them