Rogue Engineering provided adapter plugs to install 1/8 NPT-threaded VDO temperature senders in the trans and diff drain plugs. The VDO sender included with the gauges replaces the engine oil drain plug directly. I bought extra senders, as well as Red Line oils, from McKenzie's Performance Products. I routed the differential sensor wire alongside ABS sensor wiring for a while, then the rear brake line. I wouldn't tie any electrical wire, even very low-powered, to a fuel line.