Well, today was interesting. I was going to change the oil and then do a fluid change on the trans also seeing that I was going to install my B&M trans cooler. Well, I got under there and low and behold the prior owner had mutilated the drain plug bolt head something terrible (I just got this Tahoe 2 months ago). I tried everything I could but no luck. So I had to take the pan down the old fashioned way, full of fluid. Once I got it out and cleaned up I tried again to get the plug out but it wasn't going to budge. To solve the problem and never have to deal with it again I hammered a 9/16 socket on the damaged bolt head and welded it to the flange.....problem solved! The plug came right out. Now the next time I have to drain the pan, all I have to do is put an extension in there and take it out. This worked so good I may weld a socket on the drain plug for the crankcase on the next oil change. I got the B&M cooler installed with no issues and no leaks. What a day!