The axle shouldnt be close at all to hitting the engine cradle! There should be about 1-2" or more of room between the axle and the cradle and should never be questionable to worry about. If you cant stick your finger between the axle and the cradle then it is sitting way too low. The lower engine mount is on the passanger side just in front of the axle and when they age or get soaked with engine oil from a leaky engine they will collapse and drop things down a bit so make sure it is dry and in good shape. Otherwise i see a lot of aftermarket used and new axles go bad in as little as 5K miles regardless the warranty. There are brand new axles available at most auto parts stores for the $100 range with a lifetime warranty but they arent near the quality of an OE GM axle.
