any info for: sanyo m9880ka 1983 ?

hello all.
yesterday I scored this pretty cool looking box.
its only a single deck but it has nice features - and as a bonus it works.

there are some features id like to know about tho if you guys have any info -
on the left side there seems to be a black switch with 3 positions that are 1/2/3 with beat cancel next to them
what is the function of this ? and below the large headphone jack is a spot what looks like a pair of mini headphone jacks that read L and R and have ext sp min 4 ohm next to them. are theese hookups for external speakers ?
and if so - what range of hz do they play at ?

quick pic

does any one know of what type of plug it takes to go left and right for the auxilury speaker spots ?
it seems like it might be a standard mini headphone style but id like to be shure before I buy some.

todays pictures of the box

Yep, they are the standard mini plug. They can be bought at RadioShack and other type electronics places. The only headache is most external speakers don't come with mini plugs - they usually have RCA plugs or no plugs at all. Either way, you will have to do some cutting and splicing if you want to use external speakers with the Sanyo.