I have a 1972 142E with a bw35 transmission. A few days ago I bought a 16 foot daysailer that weighs in at about 600lbs with the trailer. I know my car can pull this amount. However I do not know how to hook up the hitch i have. I have what, I believe is a factory hitch, it mounts onto tyhe car using the same six bolts as the bumper and onto the bottom of the trunk right behind the gas tank via two bolts. Does anyone have any tips about the installation of this hitch? Especially regarding the drilling of the two holes near the gas tank. I want to make sure I do this correctly. Also what size and thread engagement is used on the bumper, the originaly bolts don't seem to be long enough to bolt through both the bumper ant the hitch? My second question regards the wiring. I have a four prong plug leading to the lights on the back of my trailer how can I get this system to plug into the light, brake�@light, and turn signal system on my Volvo 142E? Again if anyone has any general tips on the installation of this plug it would be very much appreciated. Thank you all for any information you can provide.