How to convert the Delco-Remy 10 or 12Si series alternator to 6 volt Positive ground.
Converting GM based alternators to 6 volt positive ground is easy. Below are two pictures of the inside of the GM based, Delco-Remy type 10-Si series alternator in both negative ground (top picture) and positive ground (bottom) versions.negative ground components installed positive ground alternator configuration
The negative ground 6 or 24 volt GM based alternator is configured the same as the standard 12 volt negative ground alternator. Note the position of the white insulators on the three screws securing the brush holder assembly and voltage regulator. The third screw near the top of the photo does not have an insulator. For the 6, 12 or 24 volt positive ground application you must wire the alternator like the one shown above. Note the three screws that hold the brush holder assembly and voltage regulator, all three are insulated. After you have installed the positive ground rectifier you must wire the alternator using the red jumper shown above. The voltage regulator in these positive ground alternators are still negative ground. The only component that makes the alternator positive ground is the rectifier. The red jumper wire is connected between the (negative) "Bat" stud on the rectifier to the ground screw for the voltage regulator. The ring terminal on the red wire must contact the ground clip on the brush holder but be insulated from the screw. 
Also, when installing the stator and connecting it to the rectifier as shown above on the right side of the picture where the three nuts are. These 3 stator terminals must be lifted a bit so the rear of the terminals do not contact the finned part of the rectifier. The stator leads shorted to the rectifier or inside case is a common problem. Once the alternator is complete and installed on the vehicle you may need to excite the alternator for the first time. To excite the positive ground alternator you run a jumper from the case (positive power) to the #1 spade terminal on the alternator. With the vehicle running you momentarily touch the jumper from the case to the #1 terminal, then alternator should start charging. After you have run the vehicle for a bit at above idle speed the voltage should build to around 7.5 volts.Hope this helps,
Randy
6 Volt Conversion/Repair kit contents:
# D1-10SI-SE6VCK, 6 Volt negative ground Conversion kit for the Delco-Remy 10-SI alternator contains:
1- Heavy Duty, low RPM cut in, Self-exciting 6-volt voltage regulator
1- Brush Holder Assembly
1- Heavy Duty Diode Trio
1- Negative Ground Premium Rectifier
1- Rectifier ground screw
1- Positive Battery Post
2- Battery post nuts
1- Battery post insulator
3- Brush Holder/Regulator screws (2-insulated 1-noninsulated screws)
# D1-10SI-SE6VCKP, 6 Volt Positive ground Conversion kit for the Delco-Remy 10-SI alternator contains:
Same contents as above kit except contains Positive Ground Rectifier instead of negative rectifier
# D1-10SI-SE6VRK, 6 Volt negative & positive ground repair kit contains::
1- Heavy Duty, low RPM cut in, Self-exciting 6-volt voltage regulator
1- Brush Holder Assembly
1- Heavy Duty Diode Trio
3- Insulated Brush Holder/Regulator screws
1- Instructions