Sent Driveshaft Shop two cheap (~$20/ea) early G50 Q45 axles from a junkyard and had them install their upgraded shafts. Paid them $50/each to do the install with new boots, etc. Worth every penny. For anyone looking to do a 3.54 Q diff though...it really is kind of sluggish through the gears now (with F-body T56). I can see the damn 1/4 line while I'm shifting into 4th. Making 440 wheel N/A (119 mph 1/4) and went 127mph on a progressive 75 shot, but still the wrong gearing (For me). But, yes, cruising on the highway under 2K rpms is not bad. One good thing about them is I suppose it's not hitting the tire as hard so you may get better traction.
http://www.driveshaftshop.com/import...r-upgrade-2193