55er

At 273,000km the transmission had a worn K2 bushing and as it turns out engine coolant making ingress into the transmission fluid.

Rebuild was around 7k AUD, but they wanted it fore a month and had to take it out and send it across the country - I'm sure they would have done a great job but it just didn't stack up.

So I did the research, my google and duck duck fu are strong, and ended up getting a second hand one out of an S430 that had done 150,000km, and came with 3 month warranty, for AUD $800.

I haven't picked the car up yet but my repairer who fitted it rang today and said it all shifted fine, no probs and was like a new car.

I pre-emptively changed the radiator maybe ten years ago to avoid the intermingling, now I'm thinking to split the cooling systems.

Basis of selection was anotrher W5A 580 box, the ratios go with the torque ratings, and there a few lists around for what 722.6 variant is what. 580s are a little hard to find in Oz, but they are around.

Should get minimum of 100,000 km out of this one, if not double that. Happy days.

RKP Waco

7k for a rebuild? What a bunch of crooks. A complete overhaul kit is $650, plus assorted bearings, bushings and fluid. All the parts to overhaul is around $1200, the rest is labor. Once the transmission is removed, it takes me usually 2 days to take it apart, clean it, reassemble it and have it ready to go back in. I have done it all in one day, but that was an easy repair.
If you have a new radiator, no need to split the cooling, unless yo just want to.

55er

That is AUD, so like 4.5k USD, and it is Australia, so that price included 10% GST and labour is hell expensive compared to US. A transmission tech might easy get AUD100k a year in the city if any good, out in the mines maybe AUD200-220k.

Plus, I dont know what they were doing but they said they wanted it a month - I have seen other people say mercedes are prone to changing various internal parts and sometimes you only find out once apart and then you might need to order another kit etc. A couple of guys who seemed to have the tools and experience said due to this that they just dont bother rebuilding anymore and just get a low km spare and bolt it in.

So all up looks like it has worked out pretty good, very noticeable improvement in power and shifting. I am just about to try the Ultimate Nag 52 third party TCU out on it, can do super quick shifts.