Gearbox breaks at 110,000km on Yaris 2007

[sven337]

Hi,
my Yaris (NLP90L-CHMGXW), @110000km, recently started making noise that came from the gearbox, and within a few hundred kilometers the gearbox became unusable. Even in neutral, the gearbox makes a lot of noise and resists movement, 1st and 2nd kinda work but with a a lot of noise, rear does nothing at all, ...

First of all, I have a problem with a gearbox dying @110,000km. That sounds awfully short to me, and although I can attest that the car had been driven pretty aggressively (and the clutch was recently changed), I don't think that's quite normal. I've seen a few threads about this car that said that one of the ball bearings in the gearbox isn't well designed, and wears out after around 100000km. Thoughts on that? I don't expect Toyota to readily agree that they screwed up, but I'm curious.

My second issue is that my Toyota dealership is being uncooperative. They quoted about 4000 euros for a gearbox replacement, which is roughly equal to the market value of the car. When I said I wanted to replace it with a used gearbox I would provide, they refused to confirm which exact model would be compatible.
Most used car parts shops are telling me my car uses a C53 gearbox (one I was offered bore the following marking in addition to C53: Y61000315, another was Y80807426. That's probably a serial number though.). I'm aware that there are several variants of C53, I'm speaking here of a gearbox pulled from the same model of Yaris with the same engine.
According to http://www.toyodiy.com/parts/p_E_200...MGXW_3301.html, I believe this is correct (OEM reference 30300-52442) and that is the gearbox my car currently has. Most shops are adamant that this is the correct gearbox, and that Toyota is wrong, or lying to me.

Toyota quoted a C50h gearbox, with OEM reference 30300-52551. I haven't found anything on the web about a C50h gearbox, and the OEM reference appears to be unknown as well. The person I had on the phone refused to say whether a C53 would work or not, even when provided with both my VIN and the VIN of the car (the same model of Yaris!) the C53 came from.
Somebody else suggested to me, on the phone, that there are two different gearboxes for this car, that they are incompatible, and that one of them has an aluminium 5th gear carter while the other uses iron. I haven't been able to examine the gearbox yet, but I'm surprised about the incompatibility. Does anyone have more information about the C50h and its differences with C53 in a Yaris?

I'm having the current gearbox removed to check its markings, so I'll have my answers soon enough, but I'm curious to understand the inconsistency, and really annoyed with Toyota refusing to answer completely and truthfully. (No doubt because they prefer to sell me a new gearbox at the price of car, rather than install a used one at 92 euros per hour of work. I "retaliated" by having the car removed from their garage, to a place where they'll do the replacement at 50 euros per hour.)

Thanks!