I used Van's "throttle / mixture" quadrant hooked up with 4130 pushrods tapped to receive threaded rod to fit the clevises. Using 4130 kept the diameter down for clearance through the bulkheads. I've seen them with 3 levers, but the third pushrod had to go inboard of the bulkheads with a cover. Hardest part was hooking em up once the fuselage was fully assembled...
The rear lever from vans looks just like the front throttle lever.
I purchased the rear assemble from vans and then bought this lever and plate from a forum member.
Much better looking in my opinion.
If you want a "normal" throttle lever back there do it like Tim's, straight levers recessed into the sidewall. Seems like passengers tend to bump the standard Vans rear seat throttle with their knee.
Don't know about you, but I jump a little when the engine note changes and I didn't do anything
I used the standard vans throttle and cut it down a little bit and bent it so it would be less likely to hit the GIB's knee and yet be able to be used by the GIB.