I acquired a pair of white top 61 ranchers. 1 has the tillotson 163 carb on it, 1 has a walbro. I got a carb kit and fuel line/filter for the 163 and its up and running. The walbro rebuild kit has been harder to locate. I was thinking of just buying another 163 and putting on it instead. Doing some reading here it became apparent that there's another tillotson that was used on later 61's. My question is: What tillotson should I replace the Walbro with? I dont have intentions of doing anything with the P&C at his point as far as upgrades go. Im just looking for the best plug and play option for this saw.