Ok I did timing chain job today on my 2007 F150. I notice when I put the tensioner on they had left and right. They look exactly the same. In fact they are and no difference then the other. What would happen if they were put in the wrong spot if they are the same? Thank you for your info....

 

I really haven't looked that close . I have been under the assumption that they will bleed oil off if on wrong side ? I prefer the old steel ratcheting style with no seal to blow out . Note that L is drivers side and R is passenger side .
If you look on the back the oil gallery is different so its going to not match the engine gallery /feed etc . Good question . I always tell guys its easy to get messed up using l/r designation as it is reverse from mechanics perspective . L and R are from drivers seat. I'm looking at the steel ones now that are cast , I don't have spare plastic ones . A smarter guy will give you a better answer .