Originally Posted by pakattack461

I have an 05 SRT6 and the differential blew up a couple weeks back so after some seraching I found that an SLK320 differential fits and it has a lower gear ratio. So, I bought one of those, stuck in on the car, and now I'm getting a code that says "incorrect gear ratio" and the car won't shift into fourth or fifth. Is there any way to flash the TCU to accept the new gear ratio? It's a 3.27.