Well I have an AW-4 and a NP231 t-case sittin in my Jeep. Both are 23 spline. The t-case is on its way out. 175,000 miles, I'm gonna say it did its job. The low range was 2.72-1. Do the Toyota t-cases have a better low range and if so, do they come in 23-spline. If both of the above are true, how hard of a swap would it be? I know enough about Jeeps but am almost blind when it comes to the Toyota.