Originally Posted by jzk25
4L80's etc don't grow on trees in Australia. If he wants a 4speed auto it would be better to stick the original Aisin box in there as they are common as dirt and easy to build strong over here. The T400 came up cheap and is simple. It'll work fine, it's not meant to be an all round vehicle that does everything well, it's meant to be a ****box with a turbo V12 in it that does skids.
I use a t400 in a jeep truck with a sbc. I switched to the t400 for reliability. I started with the jeep t90 which didn't last long then a saginaw passenger car 4 spd with a hone overdrive that also didn't last long. The difference was a 400 rpm increase at top speed from converter slip. I haven't had as good of experience with the 4l80 as far as durability. I have yet to find a knowledgable 4l80 tranny shop for high hp and torque, There must be some though. I spent 1700.00 on the last one including converter anf it overheats probably from running the pressure to high as it has hard shifts.