Did all the 64 Darts come with Spark Plug Tubes?

update your engine is 1974 or newer, see copied from allpar.com


Spark plug washers: only to be used on slant sixes from before 1963, after 1974
Most notably (and thanks to Ben Deutschman of the Slant Six Club of New York/New Jersey for pointing it out), 1963-74 engine owners should not put on spark plugs with the "crush washer" (the loose metal washer at the end of the plug). When buying plugs wtih preinstalled washers, they should take off the washer first, if they have a 1963-1974 engine. Owners of engines made during these model years should also replace the plug tube seals when changing the plugs.
Before 1963, the crush washers were needed. Then, in 1963, the slant six heads were redesigned, with a new relief at the top of the spark plug hole. According to Daniel Stern, the spark plug tube acted as a seal with this design; using the crush washer moved the electrodes so they're incorrectly placed in the chamber, while interfering with heat transfer from the plug to the head.
After 1974 (starting in 1975), the head was redesigned, the plug tubes were eliminated, and taper seat plugs were used. As part of the 1975 change, if you plan to replace lifters, you must do it while the heads are off.

link to more / 6 stuff http://www.allpar.com/slant6.html