Pulleys interchangeable?

[Swing]

I think the above link is not complete?

Originally Posted by CTScott

The European EPC shows different part numbers for the crank pulley for the 1NZ versus the 1SZ and 2SZ (which share the same part number).

Yes I would expect different part numbers, I guess al that is important if the bolt is the same, and of course the belt width and number of groves.

Originally Posted by cali yaris

The only reason to use an underdrive is to save weight. My pulley is lighter than NST's underdrive, but stock size.
Also, read up on here about NST pulleys breaking and their lack of customer service following such failures.

Why is that the only reason? 10% underdrive means (at least for the water pump) 10% less power needed. (and of course, also 10% less cooling power).
I read about the NST and poor customer service etc.

You are right from the weight point of view, but I also want it to use less power. So lightweight + underdrive is better it seems to me.