How do you replace the flywheel for automatic trans for Toyota truck?

Short answer: pull transmission and torque convertor out of vehicle and the flywheel is bolted to the rear of the crankshaft, unbolt and pull off, reverse all to re assemble. Did your flywheel loose teeth? And as such the starter will not engage? That is about the only reason just a flywheel alone on an automatic would need to be replaced.

If you need step by step instructions on how to change the flywheel, it is a long explanation, that I will be happy to write. Do not attempt to do this if you don't have a good tool set, need not be like a professional but pretty decent set. proper jackstands also, you will be under the vehicle a while. A helper will save you a LOT of time. Write me at this email: ruffy@bak.rr.com if you really need instructions and I will , well, literally spell it out for you. I have done several of these jobs and know how. All I ask is no junk mail from others sent to that address. I am happy to help.