I need to upgrade charging system in my dart .It has stock alt. What size shoulod I go with for electric fuel pump, electric water pump, 2 electric fans, msd.Car is street driven so it has lights etc. Thanks

I think 80+ Amps, but you need it to putout a large percentage of the rated current at low RPM.
This can be done by changing the crank/alternator pulley ratio. When choosing the pulley ratios you want to make sure ther alternator is not over reved at peak engine RPM. This is one reason I like the newer Denso alternators usen on most of the new Mopars. The Denso alternators are rated to 14,000 RPM, so even with a 2:1 pulley ratio you should be good unless the engine normally revs way over 7,000+ RPM.
You will also have to upgrade the wiring. As a minimum run a 10-AWG (or larger)wire from the alternator output to the battery (should go through a fuseable link too)while also connecting the stock alternator output wires. The new wire will create a parallel circuit to the battery, but will have lower resistance so it will carry more of the current than the stock wiring. The only problem is the stock alternator gauge will not move as much so you should add a voltage gauge to monitor the charging system.
The stock electronic '71 and up voltage regulator should work fine to control the alternator, but you will need the plug-in connector for the alternator.

The newer Denso alternator is a popular swap. It comes in 90 and 120 amp versions, and has better idle/low speed charging characteristics. If you request an early D150 application, it should come with a standard, double-groove pulley (not the serpentine belt pulley) and work with the regular voltage regulator setup. The D150 version has two studs for the voltage regulator wiring. You can cut off the female spade terminals on your harness, add ring terminals, and you're good to go.

If you haven't done so already, I HIGHLY recommend putting your fuel pump, electric fans, etc on relays with separate power leads. I would also run a "charge" wire from the alternator to the positive terminal on the starter relay on the firewall. This will remove a big portion of the load from the factory harness/fuse block. The weak links in the older mopar electrical systems are the bulkhead and amp meter.

If you do a search on this board about headlight relays and denso alternators, you should find a lot of good information.

I would suggest at least 100 amp peak output. THis should ensure enough output at low speed.

So if I get alt for let say an 89 dodge truck do I need voltage regulator from same truck? Also when I run "charge wire" it comes from "charge" post on alt to positive post on battery and use at least a 10 awg wire right? Thanks

I do have everything on relays and do have voltage gauge.

thanks that helped

Thanks for posting the link 64Belve