From what I have experienced and hear on the VLSD is that once the viscous fluid over heats, it's no longer a good coupler. Also the viscous fluid wears out over time. Ontop of that double negative, you can't replace the viscous fluid, you can only replace the part it's contained in. Which You might get lucky on, as the VLSD you have, is the same one found in short nose R200's. The only thing I would be worried about, is that the axles you have are the correct ones for that diff.