acquired this car with engine failure. found 50,000 mile engine complete with harness and bolt on,s. engine is in removed battery tray, plastic container under tray, disconected old harness under dash, what else do i remove to fish old harness out and new in? also have a loose vaccum hose coming from center of console that looks like it could reach to plastic box under batt. is that a good bet? would not replace the harness but previous owner complaned about elec sys and harness on replacement eng looke far better condition than orig. both eng out of 90 xj6 soverign,