Don T
Senior Member
Just to be clear 51 Merc-CT; the 2 CDN 8BA's (51 M3 and 50 Meteor) do not have any restriction of any type (except the diameter of the tubing) from the block to the interior of the filter housing. They have one drain hole in the return pipe located in about the same place as shown in your picture. The diameter of the hole I am not sure of but a piece of stove-pipe wire is a snug fit. It seems the engineers that designed these old trucks had a different thinking process depending on which side of the 49th parallel they were on?