General Discussions

On the very early pedal-start Super 55 diesels, the regulator setup was indeed a little different from the later key-start tractors.

• Two-terminal regulators (Battery “B” and Load “L”) were used on the earliest models. The generator’s field circuit was internally controlled, so you didn’t see a separate external “F” (Field) terminal. That’s why your manual shows only two connections.

• Three-terminal regulators (Battery “B,” Load “L,” and Field “F”) came in when Oliver moved to the key-start arrangement. These had the external field terminal, so the harness added the extra wire.

If your tractor is wired like the later key-start version, simply removing the wire from the “F” terminal won’t work unless your generator and regulator match as a pair. The regulator has to be the correct two-terminal style if you want to run it like the early diesel setup. If you currently have a three-terminal regulator installed, you’ll need to keep that field connection — otherwise the generator won’t charge correctly.

What to check:

1. Look at the tag on your voltage regulator. If it’s a 2-terminal regulator, keep only B and L hooked up.

2. If it’s a 3-terminal regulator, you need the field wire connected.

3. Make sure your generator matches the regulator type. Mixing a 3-terminal regulator with the early 2-wire harness (or vice versa) will cause charging issues.

So the short version: don’t just remove the third wire unless you also have the correct early 2-terminal regulator.

What Others Have Done

From Yesterday’s Tractors forum:

From New Ag Talk:

• A user running a Fleetline 66 shared that they used a small Delco alternator with an external voltage regulator, but noted it still caused the side panel to bulge a bit.

• Another suggested using a small Hitachi alternator, often used in Farmalls, which may offer a more compact fit.talk.newagtalk.com

From Yesterday’s Tractors (“Nice Oliver alternator conversion” thread):

A user posted a photo of a mini Denso alternator, describing it as “not much bigger than a softball”—a nicely compact option. Another mentioned:

Summary of Findings

OptionProsCons / NotesSmall 1-wire DelcoAffordable (~$45), often fits behind panelsMay cause light bulge on side panelsMini HitachiCompact, good fitMay need external regulator or minor wiring tweaksMini DensoVery small, clean install, can be 1-wire with modificationRequires minor wiring adjustment (excite wire)

Bottom line:Yes—mini alternators can fit behind the side panels on Fleetline (and similar Oliver) tractors. Your best bets are compact one-wire Delco units, mini Hitachi units, or small Denso alternators.

Tips for Your Conversion

1. Measure clearance behind your side panels before ordering—to ensure physical fit.

2. Consider one-wire alternators, which simplify wiring and eliminate the need for external regulators.

3. If your alternator doesn’t self-excite, it's usually easy to add an “excite” wire from the coil (+) post to trigger charging.

4. Watch panel fitment—even small units like Delcos may cause slight bulging; ultra-compact Densos often minimize this.

5. Test charging performance—during initial runs, make sure it begins charging once RPM is up (often around 1,500-1,800 RPM).