I have an SC400 trans in my LS400... works like a dream. Any early autobox from an SC or LS will bolt right up w/ no modifications except for the speed sensor. David and I "frankensteined" my LS400 daily from a shell, an SC400 trans and a used craigslist 1uzfe and loom and I never got a CEL. The gear ratio's for the LS are wider than the SC and for a truck application you may consider changing the final drive to compensate. I know out in the states we can get an SC or LS trans used for around $150.
On a side note, my pops has a 2002 tacoma and I will verify it has the EXACT SAME plug locations/pins as my LS400 trans. Your plugs should fit perfectly, but have not tried to verify for sure. A little history of the A340 series of transmissions starts with the hilux and it was used in the Supra and later the Lexus line, all the same family of transmissions. In theory you could bolt this up w/o any moddimg but it would be the internal calibration that may mess with the ECU. Well worth the try, i would be interested to see if it works!
Sean