Chances are the diffrent p/n is for a diffrent paint color on the arm. As long as in the diagram, it looks the same, you should be fine. There were some variances in design but they should all end up being the same mounting dimensions. That said, the ZL's have diffrent arms the the ZR's.

 

Pretty sure that they changed the uppers on the newer ones if not the whole spindle......im almost 100% confident the spindles are different.......That being said dont waste your money on something that may not be the right thing.....whats up with yours?? Also have any pics.....would give me a better idea to compare to my 02's arm

 

these are some pics of a arm this is the good one but i dind't think they would be different it could be for different paint cause in 02+ were silver weren't they? this is kimpex a arm that im looking at buying btw

 

Same A-arms......Different Spindles......Theyll Work