There are two Colt cylinder rod systems. Your 1978 should be the new style.
The old style requires two special tools and is risky at all times. In the old style you have to unscrew and remove the ejector rod head and then unscrew the ejector.
The new style is much simpler, but still requires care.
Put three EMPTY cases in the chambers to support the ejector assembly.
Grip the knurled ejector rod head in a padded vise, or by wrapping the head with brass, copper, or lead pads and grip it with pliers.
BE CAREFUL not to bend the rod.
Unscrew the rod. This has a standard right-hand thread.
With the rod off, remove the ejector from the rear of the cylinder.
Slide the crane out of the cylinder.
Use either a Colt ejector bushing tool or a screw driver bit to unscrew the crane bushing from the rear of the crane shaft. This releases the ejector spring and the ejector rod bushing which is inside the crane shaft on the front of the ejector spring.
As a reference, the best way to positively identify an old or new style ejector rod assembly is to try to unscrew the ejector rod head.
If the head itself unscrews from the rod it's an old style.
If the entire rod unscrews it's a new style.
During reassembly, snug the rod down tightly enough to make sure it won't unscrew, but be careful not to strip the fine threads.
How snug is snug enough is a gunsmith's judgment call.
If in doubt, you can use a small drop of fingernail polish or a SMALL drop of Loctite BLUE, NOT RED.
If you use fingernail polish, reassemble fast so it won't dry out before you get it together.
Thank you so much for the instructions, followed your instructions to the letter and everything went very well, My 1978 DS was the newer style, and I was lucky the ejector rod was not too tight and unscrewed with the "just right effort" it is all apart now and I am giving it a good cleaning. ... Something it really needed after all these years.