Everyone has been very helpful here. Have a 1999 GMC 1500 Savana with a Conversion Van Body and a recently replaced 460 Tranny with a Jasper Unit. Bottom line; the noise from my differential is incredible, its only a matter of time before it blows like my Transmission did. I spoke to a mechanic today and maybe he was joking but he said there is a product that Pep Boys sells called "Molasses" or something like that which is very heavy diff oil and acts to get rid of the noise and extend the differential/axle life, he says for saome people he puts it in and they never have to replace the axle/diff. Is he BSing me? Or is there such a product and do any of you recommend it. Or is there any other product you suggest, that would work - I need to extend the life of this differential for as long as I can. Whatever you guys suggest, I will do it (apart from rushing out and buying a new diff because according to my regular mechanic, its no different from the tranny, when it blows, replace it then as it wont do any damage to the rest of the vehicle). Thank you!