I am new to the Jeep world. I have a 97 wrangler with 35's. Was told the the gears in both the front and rear axles have been changed to 4.88's. The differential plates are leaking on both. So I was wondering first gasket or sealant and second what fluid to put back in? I have been told to use the sealant no gasket but in that case why do they make a gasket? Thanks in advance!!