I have twin 225hp mercruisers with borg warner velvet drives model 10-04. The engine serial numbers are 3563426 (port) and 3692764 (starboard) on a 1973 Nautaline 43'.
Having trouble figuring out which distributors I have. Mine have the detachable hold-down tabs with screws going through them into the _base_. They also have 2 pressed in screens in the _base_. Can't find any numbers on them. They are either mercury, mallory autolite or prestolite. Everywhere I look for parts always gives at least 3 manufacturers for the original distributors and the parts aren't interchangeable. I have pictures if needed.

And for the dumbest question of the day (I can't find a spec anywhere) what kind of oil should I use in these engines and v-drives? Boat stays in the water all year but gets winterized once it gets below 50F or so. Engines have right at 800 hours.

here it is ignore the water, it was raining

Velvet drives use Dexron. Engines use your favorite brand of 30 weight.

The only oil I used for years in my gas boats was Castrol 20-50.

Truth is what ever your favorite brand will meet engine requirements.