Anyone know if the drain holes in the block are petcocks (sp?) (like a radiator type) or more like a bolt that you need a socket or wrench to open?

They are like brass wing nuts - similar to a radiator petcock but not.

I found that a 1 inch socket (or there-abouts) and ratchet will slip over the "wings" and make removal easy.

PS - its Mark IV, not Gen IV. Gen started with the V - go figure

Could be either depending on the year. If you are draining (for winter) assure the passage is not blocked by sticking a wire coat hanger in it.

I generally use a small adjustable wrench on them. Be sure to save them. Those are the good petcocks and they are getting hard to find.

are they towards the front or rear? btw, they are of a 1990 vintage.

Petcocks in center of block jacets between3 and 5 and 2 and 4 cyclinders left and right one above oil cooler left side other 12 inches back of fuel filter and pump . Make sure put wrench on brass sleeve and also one on plug. Best to back petcock all the way out or sand rust gets in threads and next year they will be a bear to remove.

my 1990 454 and 1997 502 mpi had the wrench style 6 sided plug.9 /16 wrench.My 2001 500 efi has the blue plastic plugs a lot easyier

My 1991 454 mag has the plugs not the petcock.