HELP: School me on 2 speed rear end ratios

[Bigdually]

I'm having an issue finding info on the internet, so here's my issue.

Recently bought a 79 C70 with a Spicer 5 speed/Eaton 2 speed rear. The SPID label lists the rear gear ratio at 6.50. Is that the high or low side ratio? What's the other ratio?

I've attached pictures of the SPID label, the stamped numbers on the differential, and the plate on the 2 speed shift unit.

Thanks for any help you guys can provide, although I've been around larger trucks my whole life I've never had one with a 2 speed rear.