The alternator conversion works great, but I have a 73 with the fuel pump relay that stays on. I have done a toggle switch on the yellow power wire but this is not a great solution. I want to do a Bosch relay, that uses a switching wire from the on side of the ignition switch. I just can't figure out the Bosch relay. I think the yellow wire that feeds power to the FP relay should be wired 30 in and 87 out to the relay. Do I switch the Bosch on with 85 and ground 86 or the other way around.

The polarity only matters if the relay has a built is fly-back diode. This an option, most do not have this feature. Test with a multimeter to determine or connect pins 85 and 86 to the battery through a taillight bulb. If the relay has a diode the lamp will light in only one polarity. If there is no diode the lamp will not light at all.

Have the positive side (downstream from the switch) on 86 and the ground on 85.

I think they got you handled.

if you cut the yellow near the relay, then yellow from the VR to 30, yellow to the relay on 87, ground 85 and run an ignition wire to 86.

Basically what all ya'll said.

Dave

Big Thanks