Farmall Cub

Heres a pic of 1 of my 186 planters, the wheel measures 20" and the 184 measures 16"

There was a 20" wheel option for the 184, probably not common on a Cub.

The 184 manual may be as close as you can find easily. Most of it will probably be close enough. Seed spacings may change a little due to the wheel size or what sprockets you haver.

Binder Books has a couple of different 186 planter manuals available inexpensively.

https://www.binderbooks.com/ihimplementsmanuals.html

Jensales sells a repro of the service manual but it's a bit pricey and covers multiple models.

https://www.jensales.com/products/international-harvester-186-planter-service-manual.html

Thanks for the info
I downloaded the 184 manual it has spacing charts for
Both wheels.

For some reason the PO was putting out fertilizer with
It.