lol
redline is a brand of oil, i'm guessing blue lightweight shockprooof is the name of the oil.
around 2k for a 2nd hand gbox.
http://www.perth-wrx.com/vb/former-workshops-forum/25898-parts-west-engines-gearboxes-diffs-ect-sale.html
also, the clunk could be the clutch engaging... sometimes mine does this when i dont change properly