The part number is 84790-13020. There is only one switch to suit your car. If you need any help let me know.
Cheers Steve.
I taught it was strange myself the Toyota dealer telling me that as my car was built in April 1998 apparently Toyota changed the physical layout or else the pin out of the switch at this time.
I just want to be 100% sure on the correct one before ordering it, here is as much detail as I can give you on my switch at the moment if it sounds like the one you have given me the part number for please let me know.
I mistakenly wrote last night that my rear demister switch was on the LHS of the driver’s wheel under the indicators stalk, when it is in fact on the RHS of the steering wheel under the light stalk.
I looked at the switch today and the pin out is 4 pins in total "depending on which way you hold the switch it looks like this" pin number 1 is in the top right hand corner with pin number 2 to its right then the third pin is directly under the second pin then a gap then the fourth pin down the bottom.
I will get pictures of the switch tomorrow post them.