The iboats forum moderators are excited to announce that at this time it appears the iboats forums posting pictures function is working once again. Though we cannot promise for how long, we're hoping for indefinitely.
Tohatsu/Nissan OB's are not identified by year of manufacture. The model is what you need. I assume it's an M5B (internal tank) or M5BS (external tank). Figure 20 Kg... roughly 45 pounds.