Hmmm...

I always thought the single sided swingarms were all the same (except the black S4Rt). I'm looking at 37010343A which belongs on an S4R (996), but the seller says it came off an S2R.  37010344A seems to be the correct number for S2R.

Important differences?

37010343A and 37010344A are both valid part numbers.

Latest part numbers from live parts info is 3701346A for silver, and 37010346AB for black.

Dealer will be able to give the final word on what the latest part number is.

I've never seen any functional difference between any of them in person or online.