I didn't trust the collars, so I solder it. That's how it is on the GPcap232 .40 and some other arfs.
If you don't have a torch you can wrap threads over the two rods and CA it. Still use the 2 collars thou.

On my Ace 4 -40. A dowl is used . Two rods to form a Y on the tail end and one rod on the servo side.
Threads wrap around the dowl and rods to secure it. It dose the samething.
Screw the cleves after you sholve the rods through the fuselage and adjust it accordingly.

To convert it back to a single rod. Just use Music wire to joint the elevators....a wide U shape.

But the dual rod system is better becuase you can adjust on both of the elevators
Sometimes when jointing the elevators...the holes I drill into the elevators to insert the U shape music wire arn't exactly striaght. (single rod)