I have only 1 system to use. Where can it be used more efectively on the rudder , or elevator. thanks for any imput.

Just because the lines come out either side of the fuse. If you used it on the elevator, you have to have a "high" and "low" line, and one will need to go over the top of the stab.

On the rudder, both lines usually come out under the stab, out of sight (for the most part).

And it is lot easier to set up/adjust with the bellcrank horizontal as opposed to vertical..IMHO.

But pull-pull is sweet when set up right.