I have use rtv a few times now between my crawl box and t-case, and between the tranny and crawl box. I have had no leaks and no problems. I have always had gaskets between everything else, but see no reason why you couldn't use rtv there too. If you do use gaskets I would definitly use toyota gaskets. I copied the folowing off of trail gear's website that you might find interesting
( Gasket Warning: Please use only Trail-Gear provided or factory Toyota gaskets. You can easily tell the Toyota gaskets as they have green lines on one side. Some aftermarket gaskets do not have the proper oiling holes. Use of these gaskets in any dual adapter will result in failure, sometimes in as little as 5 miles. The result of this failure is that the bearing melts down and the drive train suddenly locks up after just a few miles of driving. This could easily cause an accident. Please don't use gaskets you have hanging around your shop or gaskets from other brand kits, unless you see the factory green stripes.)
this might be more info that what you wanted, but i hope it helps
Jon