Sorry it took so long to get back to the computer.
I think the questions were already addressed above, but I'll itemize them here:

Most parts stores with an able bodied counter-person could probably just go to the box based on you saying I need a 70a Ford alternator.
They were available in this form from approx. '73 to '92 on cars and trucks, including Broncos and Pickups with the 4.9 engine.
But for general purposes you could ask for one from a '79 Bronco or F150/250/350 and see what comes up.

The most common number (semi-standard industry number) is the #7072 which is clocked at the 9 position. There is a 7072-3 that has the connectors at the 3 o'clock position too. You could look at both to see if one lends itself better to your application, but the standard one was what would have come on your engine. I forget if the clock position is viewed from the back or the front, but you can take one look at it out of the box and know what's what.
The connectors are generally more accessible than the small case, but it's certainly possible to be in the wrong place for any one particular setup. So check.

No, I used my existing one. However, I already had the modern electronic version vs the original electro-mechanical points version. I think that makes a difference and so you should at least make sure your regulator is the modern type.
This is usually indicated by the lower profile of the top cover. If yours is roughly 2.5" tall, it's possibly the old style. If it's about .5" tall, it's the new style. The low profile is a guarantee, while the tall profile is not, since some manufacturers kept the old looking one with new guts for awhile.

Yes.
Depending on the brackets used. I still have not seen a pic of yours, so am not guaranteeing anything. Your results may vary...

Yes.
Used to have them on the electric parts rack, especially if they carried the JTT brand connectors. But I have not seen them as much lately and grabbed one the last time I was in an independent shop that still had them.
Probably the old school NAPA stores might have a good chance of having them. Otherwise they can still be ordered.

Paul

 

1TonBasecamp -- Paul, thanks for taking the time to give me some more information on upgrading my alternator to a 70 amp big case unit with a newer style electronic regulator. Don't know if I had told you before that I had a stroke two years ago and I have to go over things a bit more these days just to get a good understanding, thanks for the extra effort. Tom

 

Not a problem. Even without that event in your recent past, electrical stuff makes most people zone out after about the third sentence. Or at about the "It's simple. Goes like this..." part.
Sorry I did not have the part number for the "pigtail" (connector with wires already) but it's been awhile and I was being lazy in not looking for one. Hmmm, I wonder if I still have one in the package? I'll take a look!

And for the record, when I read your first comment right then, I thought you said that before you were working on the truck, you had a "2-stroke" years ago!
Thought that was kind of a strange comment for this discussion, until I actually re-read it and saw the error of my ways.

good luck. But have fun too!

Paul

 

Bingo! Kept just the label in my electrical drawer. Last one I got was a Pico brand, part number 5331C Ford alternator connector.
If not local, searching that number immediately brought one up on Amazon.

Paul

 

Skip the big case 1g, do a 3g swap. No flicker and very easy install. Best of all very cheap swap.

 

Well there's that too of course. But keeping it old school is still a legit option as well, with a slight upgrade from original.

Paul

 

Paul, I found the Pico Ford Alternator Connector on Amazon as a 5331PT for $10.16. I will pick one up this week & check with NAPA on a big case 70 amp.

ford390gashog -- I have no problem with my current 65 amp 1G small case alternator, have replaced & upgraded front headlight harness, no flickering. 3G are great for those that need them.

 

Way back in the mid or late '70s I did a 1 wire 104 amp swap with an internal regulator. I used a GM Delco and adapted it to my mounts. It's been going ever since.

 

Alex from GA -- Thanks for the reply, do you have any problem with draining the battery if the unit sits for a long time with the field being energized all the time? Or is yours wired that way?

 

It's been so long I don't remember how it's wired but the truck sits for several months occasionally and still starts. I haven't measured the voltage before and after. I just remembered I had to add a diode to get it to exite.

 

with the aforementioned light duty, you don't really need a high-output alternator at all, regardless of whether its a 100-amp 1G, or a 95 or 130-amp 3G.
why not stick with what you've got? no need to reinvent the wheel.

if you really just want to switch to an internally-regulated model, just go with a Delco 10si in your existing amp range. super cheap, readily available, very reliable.

 

Alex from GA -- Thanks for the additional reply.

rustywheel68 -- True my 65 amp is working out fine as it is correctly. With 85-90% town driving the truck is idling a good part of the time. The large case 1G alternators charge better than the small case at idle. I think this is the way I'll go. Also with my "old dude" eye site I don't drive at night much any more so my battery / alternator draw is very low.

 

Is the Motorcraft GR-540-A regulator a "Solid State" unit?

What is the difference between a GR-540-A & GR-540-B?

Will they work with my 65 amp small case regulator on my 1971 F-250?

 

No idea, but NumberDummy might clear that up. Very possible that the "A" is the old mechanical points type, while the "B" is the newer solid-state unit.
If a 540-A unit happens to have the tall cover, and on the back of the unit you can see resistors, connections, and all sorts of mystery items hanging out underneath, it's a good chance that it's old-school. An exception to that might be if someone is making them look like the old ones for restoration purposes, but inside is the new solid-state stuff.

But either way, either will work with both alternators. With the solid-state having the advantage most likely.
So stick with the solid-state, in my opinion.

Just so that you have all the info to work with, a 3G is a very good low idle charge unit as well. Just in case you were thinking that the large 1G had any advantage over the 3G in the charging department.
Not trying to talk you into one over the other. Just making sure you have all the info at your disposal.

Paul

 

Ya, I hope NumberDummy can tell me the difference between a Motorcraft 540-A &
540-B regulator & are they both solid state units?

Paul, thanks for the heads up on the 3G at idle charge. If I could find a 3G cheep & wiring was not a big deal I should still look at one. If I have to replace wire harness under the dash that's a big deal. We will see what I come up with.