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04 WRX transmission help

899 Views 3 Replies 3 Participants Last post by  XJman

Total Subaru newbie here. My daughter has an 04 WRX. It came with the 6 speed STI transmission (TY856WH3MA) when she purchased it. We recently brought it to the transmission shop due to noise. They have pulled it apart and said it's a mess. The estimate is around 7K just to rebuild it! They said some of the parts have to come from Japan?

I'm used to Toyota's, Honda's and American cars where parts are easy to come by and cheap. He said the center differential alone was $2,500. Anyways, we are looking for a replacement transmission and have found several from different model years but not the exact swap that was in the car. I was wondering which Transmissions can be swapped and be compatible. Again, total Subaru newbie (I do know a bit about transmissions and other cars but not this one). We have found a T856WB6KA and a TY856WB1CA. The KA has the same differential types as the current transmission but the CA has a Viscous center differential. Does this make any difference?
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You have a 2004 STI transmission with the dccd. I would replace it with exactly that.

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The JDM transmission will likely just have shorter 5th and 6th gearing

I have one of the CA transmissions and it has been great for years even at the track.

If you have all the wiring for the DCCD gearbox then you might as well get the KA box.
Here is a reference for the older transmissions. Should have the codes, gearing, final drive, and center diff info. Transmission Chart

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