Hi,
I have just changed the t/stat on my 3.2 but I undestand t/stats are the same as yours.
Check you have the seal ring for the t/stat housing as mine didn't come with the seal.
Also, there have been some slight changes to design, the later version has a thinner flange on the housing so original bolts may be too long. The rear bolt screws into a blind tapped hole so unless you shorten the bolt it doesn't tighten down on the flange.
Be prepared, you may have to replace the transfer pipe as well, I have seen a couple where the seal rings have been slightly leaking over a long time and corroded around the seals and difficult to get watertight even with new seal rings (there are 2)
It is difficult to get to the bolt holding the transfer pipe, especially with a Torx socket/ratchet. if you have one of the old imperial size 3/8 ring spanners this will fit OK and be easier to get at the bolt with.
Roger