Oil Temp Plug....Best place and way to install?? (LS/Vtec)

Is there any way to determine if a YS1 is the LS USDM or the short gear b16 with LSD, without cracking the case? Serial? Stamps? And the LSD, can I see it in the Axle shaft hole?

I have a LS YS1, and someone wants to sell me what he says is a rare JDM YS1 with LSD. They look Identical from what I hear, so how could I be sure? Or can I?

THANKS!!

BSR