'82 C30 Speakers?

[lgvl]

So my dash speakers are blown and i can't live without having at least partially clear music while i'm driving so of course i'd like to replace them. Well i start flipping through my truck's shop manual and wind up on the speaker section and it shows my truck but doesn't list the speaker size, or at least i didn't see it. So i was wondering if anyone knows the original size? I did the crutchfield lookup and it says 3.5" which makes sense but in the manual it looks like the larger 3.5" was used in a mono center speaker setup while smaller speakers were used in the stereo setup. I'd like to switch to stereo, as it seems i have groovy monophonic sound as of now, so i'm imagining i will have to run new cable to the left and right of the dash cover. So what size are the stereo speakers? Thanks guys.

P.S.- I would normally just go out and remove the dash cover and look but i'm working offshore at the moment and would like to order the parts for when i get home next month.