I had the same problem with my 307. The trust bearing is a common problem on them.
The big one is to make sure you disconnect the 2 gearbox cables off the top off the gearbox as these will break very easily

If they break they are a Peugeot part only and cost about £160 to replace. The clips that hold the cables on top of the gearbox are fiddly and will more than likely break when you remove them.
I have the HDI which makes them hard to get at but unsure what room you will have with the petrol version
