Well,surely in my 03/abs Euro--04/abs for USA,my bike is a november 03/model the rear caliper is from the 06-07-08/model..!
The bleed screw is installed in the side area of the caliper like the 06/models
I think the bleed screw in the 03/04/05 models is installed in the upper side of the caliper..correct?If the Yamaha has install for i don't know the reason,a caliper from the 06/07/08model in my 03/04 model i believe this caliper can installed in all the 03/04/05 models!Surely,if the bleed screw in 06/07/08models is installed in the side area of the caliper then my caliper is from a 06/07/08 model.!I will post a picture here later from my caliper to see..
It cost 187$ here:
https://www.partzilla.com/parts/search/Yamaha/Motorcycle/2008/FJR+1300A+-+FJR13AXB/REAR+BRAKE+CALIPER/parts.html
+1 - The rear caliper on my '05 also has the sideways bleeder screw like is shown on the '06 and later parts breakdown.
[edit - same as the pictures above]
It appears that Yamaha did a cut and paste in their parts fische and used the non-ABS caliper's line drawing for the ABS bike parts reference, as those drawing are identical, showing the bleed screw out the top, although clearly that is not what comes on an ABS bike.
Of course that still doesn't prove that it will fit, but it makes it more likely that it will.