Trojan Boat Forum

I rubbed off all the layers of paint from the transmission plate and the model number is DD 507-1A it says it's a Detroit Diesel transmission. Is this the same as a twin disc? Merger? Oil capacity 1.72 gallons, ratio 1.5:1

Its safe to say you have twin disc gears . MG-507-1A . Oil is listed at 1.72 gal. But that will vary on the angle its mounted . Also you may not get it all out . It calls for 30W or 40W oil depending on trans temp . 30W fits the bill in most cases

As far as being list as a DD vs MG its because it was sold with DD engine I believe .

This below is from a boat diesel post . With you being in NY 30W would be the choice . Unless you have trans temp gauges that say different .
"The TD manual states:
operating temp 150 - 185 degrees = SAE 30 weight engine oil
operating temp 175 - 210 degrees = SAE 40 weight engine oil
Capacity is 1.72 US gallons according to manual"

Thanks!