It's even tougher to install the block heater, try taking that core plug out after 20+ years. Usually to do that you need a breaker bar with the MB allen socket and about a 6 foot pipe, plus have some heavy friends and a torch.
With the block drain usually, like the block heater plug, you'll want to do it on a hoist from below. Usually a nice long 1/2" drive breaker bar will do it, like about a 2+ foot long one.

Gilly