Reading codes

Some questions on getting fault codes...

Is there a scan tool that will plug in and read the pre-96 Dakotas (OBD 1?)?? I ask because I've never been able to count the flashes accurately, they just don't flash right on my truck. I've noticed 2 smaller plugs hanging below the driver's dash on my '94, also on a '95 I checked out today, are those plugs for a scan tool, if so, where can i find it?

On a 96 Dakota, how complete are the codes that show up through the OBD 2 port? Last week I scanned a 96 and it showed "no codes," even though 2 vacuum lines were unplugged and the truck was stalling. Is the 96 code bank incomplete because it was the first year or something?

Thanks for any help