Forget it, Alfonso. There is no STC and trying to adapt the design first implemented in 1973 on a different aircraft -- because the 336 and the 337 ARE different -- would be hugely expensive to be legal (i.e., after figuring out how to do it, it would require, as a minimum, engineering certification that the design is safe).
Your current design, on the other hand, is safe and effective (my '69 337D had it). Yes, it requires adhering to procedure, but it works fine if you understand the system and how to use it. That's what my Fuel Management page does at
www.skymasterus.com.
Ernie