Source of cheap compact inline[ish] gear drive?

[graffian]

I want to mount a small alternator on something.
keeping it compact and without a lot of offset will be easier with
gears. I am wondering if anyone can think of a small gear drive, a ratio
of aroudn 3:1 is what I am thinking of.

 

[Robbie260]

I want to mount a small alternator on something.
keeping it compact and without a lot of offset will be easier with
gears. I am wondering if anyone can think of a small gear drive, a ratio
of aroudn 3:1 is what I am thinking of.

A transfer case out of a scrap partime 4x4 like a series landy or pick up or jiminy is probably going too be you cheapest option cant really speak for what ratio it would be unfortunately as i canny remember of the top of my head.

 

[graffian]

As I pressed post I realised I should have an old monty starter next door,
the gear train from it will be abotu the right sort of size and a sprag is a
good idea.

Turned out I had two starters, but one hasn't any gears and the other is
missing the big one. The little gear is 14t the big one is around 40T, so
the ratio is ok, just got to find the gear now.