I am in the process of reassmbling my rear suspension. The rear end worked fine its a 3:08 in my 71. The only thing that I notice was that the left output yoke just slides out. It looks as though there should be a clip on the very end of the spline.Does anyone know if its ok to leave it as is?

You are correct, there should be a c-clip at the end of the side input yoke to secure it.
The suspension will not allow it to come out, so there is no worry there, but there is a bigger issue.

With the side to side movement, it will hammer against the the cross bar inside the differential. This will mushroom the end of the yoke and makes it impossible to remove later. Also, this will cause metal wear and have odd parts floating around in your gears and clutch packs.

Hi
I would say that this clip must be installed as the joke ( halfshaft ) is holding the complete trailing arm in place.
Without this clip, only the trailing arm hinge bolt at the frame keeps it barely in position, depending on how worn the bushings are.
Try to pull on the wheel without the clip installed and you will feel movement.
Only time you can remove the clip is if you have a 5 or 6 link conversion installed.
The clips are known to fall off if the joke is worn over limits.
If that's the case, you also need to repl the output joke.
Good luck Gunther