thunderbolt IV swap

[pinerocker]

hello, i am currently trying to install a thunderbolt IV dist and module from 87 260 merc in my 77 260 merc. which used to have an automotive pontiac hei distributor in it (i know i know, very bad and illegal, i didn,t do it, the previous owner did it.) first problem i have is the wires on the 77 merc. i have two yellowish wires that were tied together going to the bat term on the hei dist. one of them reads 3v with ignition on, nothing on the other. and i have two brownish wires that were tied together going to the tach term on the hei dist. one of them is from the interupter switch the other must be the tach wire. so my question is where do these wires go on the thunderbolt coil? and doesn't the thunderbolt need 12v not 3v ? i think there is a ballest resistor in line someware knocking down the voltage so not to burn out the points(originally). anybody know where this might be? and does anybody have a wiring diagram of a 77 v8 merc w/points dist. that would help out greatly. thanks!