You have two choices for the ZF6HP21 transmission.
LG6
Mercon SP
Both are suitable for the transmission.
It is pointless to replace the pan at 60K miles unless you just wish to have peace of mind. That is a huge filter. All that needs to be done is to drain and refill the transmission, this will take a little over 5L so get 6L.
Here is a web site for the best price I know of on LG6 and the pan.
Any O'Reily's parts store can order Mercon SP for $5.99 a quart.
LG6 at about $18.00 a L.
http://www.thectsc.com/index.php?p=p...id=10&parent=0
Here is the kit you wanted
http://www.thectsc.com/index.php?p=c...&parent=7&pg=1
The reason I know that Mercon SP and LG6 is interchangeable is that ZF makes a similar transmission for Ford and also I sent samples of new LG6 and Mercon SP to Blackstone and their results confirmed that with the exception of order and color they could have come from the same batch of AFT. Many on this and other forums are using Mercon SP with no ill results...