I'm not a fan of replacing expensive parts that work fine. You state that there are no leaks or noise. Like others mentioned, some play is normal. It's a fairly complex gear system, and inevitably will have some slop.
I see nothing in the service manual about having to replace the axles when you replace the differential. That just sounds bogus.
Even if they were right (and I do not believe they are), $3000??
Here's the procedure if I recall correctly:
1. Lift car.
2. Remove wheels and brakes.
3. Remove big-ass axle nuts.
4. Remove the wheel bearing + hub assembly.
5. Slide the axle out of the diff.
6. Repeat for the other side. total time so far, maybe 2 hours if you're really taking your time.
7. Disconnect drive shaft from differential.
8. Remove differential.
So, now you're at three hours if you took lunch and billed it, so let's be kind and call it 7 hours for removal and installation. At a dealer rate, you're probably in the $90/hr rate.
Even assuming $1500 worth of parts, that's WAY less than $3k.
If this was my car, I'd just leave it as is. If it's not clunking, making noise, or leaking, and doesn't have 30* of play, it's fine.
Blue-ish 2006 2.4, Werks stage 1 turbo, Borla cat-back, DDM braces, Spec aluminum flywheel, Spec stage 2 clutch, Werks aluminum radiator, some gauges, RKSport hood, Morimoto FX-Rs, GReddy Profec, Norm's fenders
'07 GXP, Werks Big Wheel K04 and tune, Solo catless downpipe, TCE Wilwood 6 piston front brakes, 4-piston rears , stainless brake lines, slotted/drilled rotors, BC Racing BR coilovers, Performance Autowerks intercooler, DDMWorks CAI, charge pipes and braces, RPM rollbar
Last edited by raygun; 08-22-2018 at 11:08 AM.