Actually I start most of what I do with a 5.4 truck transmission if it's for a 4R70W. The reason for this is that they have the hardened gearset parts. The problem with this for the average person is that they are going to need a valve body from a car transmission and using their older one isn't the solution.
Just make sure you don't get a 4x4 truck transmission unless you are planning to tear it down completely to replace the output shaft.
01 F150 5.4L 4x4 and a 98 Mustang GT vert sitting engineless and without transmission or converter