TOPIC: Volvo penta 280 gears

Hello, gentlemen. Newbie question, probably, but I'm a bit confused here. Which set of gears in a Volvo-Penta 280 changes the gear ratios? I have an outdrive with straight six gears, need the 1.61:1 v-8 gears. I was under the impression it was the upper set of gears, but now I am seeing lower units advertised as 1.61:1, and could use the entire lower drive, as mine has a broken lower fin. Any help here would be highly appreciated.

You might check the Volvo-Penta manuals here to see if they have any info that might help;
boatinfo.no/lib/library.html#

The bottom 1/3 of the Volvo Aquamatic outdrive is where the gearing takes place.

I had a 280 with a 350 in the doghouse and think the 280 is set for a V8. But sold it so so I don't know if 1.61.1 for sure.

Aquamatic ratios--
OHC 4 cylinder = 2.15:1
Inline 6 = 1.89:1
V-8's = 1.61:1

I don't know about the diesel model(s).