Yep, anytime the bell housing is removed, that plug needs to be changed. If it springs a leak due to rust-through, it's a huge job to remove everything covering it up with the engine in the vehicle. It's a simple cup-shaped disc that's installed by coating the edge of the plug with non-hardening gasket sealer like Permatex and giving the plug a firm tap with a hammer once it's in the counterbore.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!