I am looking at buying a ranger with a 2004 optimax on it. ( boat is an 02 ranger 20vx). My question is two fold. First what is the difference between smartcraft and the mercmonitor? Second If a smartcraft has been added to the system at a later date will it still show total hours on the motor or will it show only hours counted after the install? I know that best way to go would be to have dealer plug in. however, I am going to look at it on Saturday and they will be closed. he said his smartcraft gage is showing 230 hrs which seems quite low for an 04 (16.5 hours per year) should I really be worried about it that much as long as compression is good and lower unit oil looks good. Any help would be appreciated thank you.