Transmission drain plug

What is your question?

5.7 L 350 Vortec V8 Gas 99 GMC Yukon. 4WD. Verified transmission: 4L60E w/ deep pan. In '07 i had trans mission re-built (maybe not important) and so...I am replacing a solenoid inside the transmission pan/driver's side. So i must remove pan. NO DRAIN PLUG. NO PLUG Anywhere on the pan. I see the divot where the drain plug should be however no plug has been drilled, it is a smooth divot. Could this be? Could this be a new pan the mechanic put on? What gives? Any clues on where a plug would be? How do I drain then? Di I drill hole and plug later? Can I just loosen pan? Will 8 qts of Tran fluid dump everywhere? I loosened the plug on the rear transfer case and about a cup of milky red substance poured out and that was all. This can not be trans fluid..? Not near enough, however must I replace this fluid? With the blue or red transfer case fluid? Please help soon...drain plug issue most important.