Moki 120-135 question
 

I purchased a plane from a friend that got it from another friend (This bird got around) I was told it had a Moki 135 in it, BUT when I took off the cowl getting everything ready to fly, I noticed it had 120 on the case, However Moki does have a service to have your 120 turned into a 135 if sent in. and I was wondering how could I tell if it has been made into the 135. Either way I'm keeping it the way it is because it runs like a raped ape with power to spare but it would be nice to know what displacement it is.

Dauntae