For the boost leak; I stuck a pint size paint can in the hose coming from the air filter box. Pulled the small hose off the blow of valve and gave it a short blast of air, then put my thumb over the hose and listen for leaks.
The axle, there is a thread for that in the DIY forums.
You'll need a 34mm/1 1/4" socket and a long breaker bar.
Be careful with axle seal on the tranny, if your careful you can use it over again. Do not pry against it to pop the old axle out.
I got my axle from Advance auto Parts for $80.00, it's been in there almost 2 1/2 years now.
215,000miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. CHECK your oil, these cars use it.
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