The inlet rocker arm of the later type is shorter on the shaft length than the early, also the roller pins on the early arms are slightly larger in diameter.
But as a rule they are not a big failure problem.
2002 is the last year of the earlier arms. you can't fir the later follower bearing so it has to be a whole arm complete if you want to upgrade. arms run at 89.40 each in the UK but they are complete for that and as such good value. you get 25.00 worth of tappet pads and and nuts as well as a 30.00 bearing.
I'd say keep the original set up and simply repair. going to DVSK will give everything an easier time.