Thanks. I have removed the shaft myself.
Well I took off the rear U-joint and centre bearing bolts. But kept the front portion of the shaft intact on the spline (because the transfer case fluid slowly leaks out if I take off the shaft completely - and I dont want to have to refill that)
The rear U-joint is not 100% perfectly smooth moving. There _is_ infact a little 'micro binding' but I dont think that can cause the shaft to rotate off balance to hit the gas tank sheild. This binding feels like increments in movement as I bend the joint. But Toyota has enough to defend themselves against repairing my problem because they claim this U-joint "is bad and is an existing problem that they are not responsible for". Hence they will not replace the shaft regardless of whether it started touching the tank shield after it left their shop.
My dad suggested exactly what you did -> bend the heat shield. But to me this seems difficult since it's hard pressed against the tank. I guess I will try some serious bending or hammering. I need very little clearance.
The other possible cause is the play in the centre support bearing. With the shaft intact, I can push up on the centre portion and actually cause the shaft to hit the tank shield. To me, _all_ the play comes at the centre bearing (rubber surround). Is this normal? I'm talking 1/8" or more. Perhaps that is the real problem. It certainly is not snug or tight. But not loose - just a little flexible.
Dad also suggested to add washers between the centre bearing mount and the car -to effectively lower the bearing by a tiny bit.
What do you think?
Thanks in advance!