Extend/Run the orig blue (ign1) wire to either alt field terminal & T into it back at the firewall & run that to the top terminal of the flat VR triangle w it facing up like a pyramid. then run the orig green wire from the other alt field terminal to the side terminal in the VR triangle. You can trim the sides of a flat VR & it will nestle neatly into the squarish firewall recess where the "box" VR once resided. clean the back a bit for a good VR to firewall ground & you're set EDIT I think there's a listing for a 70's or 80's M body that has an 78 amp alt. If you want to retain the single pulley an alt shop can switch them or slightly adj the spacing on the double pulley one to line it up