Educate me on outdrive gear ratios please.

[further]

Would like to understand how to determine what outdrive would work. My existing outdrive is an SX and the nameplate is completely illegible. If I wanted (at some point) to replace it with a duoprop, what do I have to look for? Do they need to match ratios? Would any SX DP work? How do I figure out what ratio my current drive is?
sorry if this has been asked before... I couldn’t find in my search attempts.
Thanks

 

[Scott Danforth]

On VP's, ratio is in lower. 5.0 and 5.7 get the 1.95:1, V6's get the 2.15:1, Big Blocks get the 1.78:1.

 

[further]

On VP's, ratio is in lower. 5.0 and 5.7 get the 1.95:1, V6's get the 2.15:1, Big Blocks get the 1.78:1.

So if I have a 2004 5.0, my drive will be 1.95:1? So would I be able to just swap the entire drive out with a SX DP that is 1.95:1 of the same vintage if I found one?

 

[Scott Danforth]

You really only need the lower unit

 

[further]

Ok understood but if I had a complete upper and lower SX DP I could just swap?

 

[Scott Danforth]

Yes