Tridon make a thermostat gasket for a 4K and the part number is TTG42. You should be able to get them from Repco or Supercheap Auto.

get a tube of gasket goo. easy no fuss and works great.

Alright thanks everyone :) this really helped :) cheers

How difficult is it to change the rear main engine seal? What would need to be done? How long should it take with the correct equipment and knowledge? thanks

need to remove gearbox, clutch and flywheel.

Would also be much easier to do with the engine out of the car.

Pull motor out, replace seal, refit motor. but thats how it starts.... "since i've already got the motor out i'll 'just' freshen it up".