To change the front seal, you'll have to take out the fan/clutch assembly; the fan shroud and drivebelt; the crankshaft pulley/vibration damper, and finally remove the old front Crankshaft Seal with care. Inspect for damage. It comes in with the open side facing in, lubricate it with engine oil, and drive it into the bore. Lubricate the lip of the seal, and install the damper onto the crankshaft paying attention to its alignment with the Woodruff key. Tighten up this bolt on a damper, put back the fan/clutch assembly and shroud, and restore a drive belt. To replace the rear seal, disconnect the battery cable, remove the drain plate then the back cover plate or backup housing. Remove the retaining ring or snap ring and discard the gasket material or old sealer.