Well, first off the model # should be on the side panels of the tractor, same as the larger American made Olivers. I have a 1355 and the serial number plate is under the steering wheel. Is it a 4WD? If so it is quite easy to tell if it is a 1355 or a 1365. The 55 series drive shaft for the 4Wd unit comes out of the left side of the transmission and the bell housing on the 4WD unit is positioned on the left side of the 4WD unit. It also has a slip clutch on the shaft just before the shaft goess into the bell housing. The 65 series has the drive shaft for the 4WD unit directly underneath the tractor frame same as the bigger Olivers. There is no slip clutch on the 65 series drive shaft. The bell housing on the 4WD unit is, of course located in the center, same as you see on all of the newer European 4wd units used on most of todays tractors. The tractor should be the green and white color combo. The 55 and 65 series tractors are very similar except for the 4WD units. the 65 series 4wd unit is FAR superior to the 55 series units. Hopes this helps you out. 

                                            Don