Husqvarna 266SE serial number 1661 17740 drum differences

[dsell]

On a Husqvarna 266SE with serial number 1661 17740, how do you tell which Oregon drum to get?

The Oregon catalog shows 102469 before S/N 0510000 crank diameter .501 bearing 11999

26831 after S/N 0510000 crank diameter .500 bearing 11893

From reading here, the SE changed to XP in 1986.

Here is some information from answer army:
The first number on the older saws is the last number of the year. Here is an example 510263. That serial would make this saw a 1985 or 95 year model depending on the color of the top of the saw made in the tenth week of the year. We have used three colors thru the years. The 70's are white. the 80's are black and the 90's till present are orange. We started using double digits in 2000. Those serial numbers start with 00. So a 2008 model would be 0812345

 

[pioneerguy600]

Good info for anyone working on one of these saws!

 

[dsell]

Just to be clear, the serial number doesn't match their system, so I don't know how to read it. I think this may have been an issue on the earlier saws. I started trying to figure out the difference in drums from the two numbers. Another thread stated there is a difference in the crank diameters. .500 to .501, is that really enough difference to justify a different system? The bearing specs I'm finding must be inaccurate or there is another difference in the drums.

 

[dsell]

TYP 266 SE ASS 2220/81
1661 17740 on silver plate
orange top cover.
Does the 81 stand for 1981? There is an IPL for 1981-09