Hi all, I recently acquired a 1972 Fargo 100. It’s unfortunately got a 318/auto in it with a dead hole and a leaking trans. I’m planning on swapping it out for a slant 6 and A-833OD. What’s a bit interesting is I’m getting the slant from a John Deere swather with the goal of getting the truck to run like a Deere. Are there any additional factors to consider when swapping in an industrial variant? I understand that swapping an automotive /6 is pretty much just swapping motor mounts and transmission. Did the industrial models have a different oil pan, will the accessories transfer over, is there a specific A-833 I should be looking for with the correct spline count, etc? I have experience in the big block C-body world but I’m very new to the truck and slant 6 worlds so any guidance is appreciated.

Hey, cool, that'll be one of the very last Fargo trucks sold in North America. Take pics along the way!

Oil pan and pickup on the John Deere Slant-6 might or might not fit in the truck; odds are better with a swap into a truck than into a passenger car. You may have some reconfiguration to do of the induction system; tractor-type applications often have governors and such that aren't appropriate for road vehicle usage. Likewise, you're going to want to have a distributor with advance curves suitable for road-vehicle use — that's just as well; the HEI upgrade is well worth doing anyhow.

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Too many people who were born on third base actually believe they've hit a triple.

I've acquired my slant 6! It's out of a John Deere 800 swather. The info I got before I bought it was that it ran 5 years ago, but it's seized from sitting. I tore into it today, 3 cylinders were full of water, 1 of which is very crusty. The rest of the engine looks great! Under the valve cover looks amazing, all of the bearings on the bottom end look amazing, even the nylon-tooth cam sprocket looks almost new. In terms of industrial to automotive conversion, it seems pretty straight forward, the alternator is on the left side and motor mount brackets don't come pre-installed. The governor is a belt-driven accessory, its very easy to remove and the carburetor seems like it can be adapted for street use. The distributor is points-style with a vacuum advance, I'm guessing it's also got a mechanical advance component but I'll have to take a closer look. If anyone wants any documentation done on the industrial slant, let me know. I've got everything torn apart and could very easily document stuff, though this is my first slant so I don't know what to look for in terms of differences.

With that one cylinder being so bad, I'll likely have to get the cylinders machined. I'll probably hit it with a hone just to see if a miracle happens, but I'm not expecting great things. While I've got it at a machine shop, are there other things that would be beneficial to do? I've heard milling the deck/head for higher compression and putting in larger valves are advantageous.

I'm trying to build this truck for peak efficiency at cruising RPM while operating on 87 octane. The rough plans for the build are something like this:
300CFM Holley 2bbl carb (from a mercruiser engine, adapted for automotive use)
Aussiespeed hurricane 2 bbl intake manifold
Headers into a single 3" exhaust
The only accessories would be water pump and alternator
A-833OD transmission
2.9 or 3.2 rear gears
All of this in a lowered single cab-long box pickup, I might try some aerodynamic modifications.

This is what the combustion chambers look like with the head off. All 3 cylinders with liquid are seized, they all have water and some coolant. I poured some ATF down the intake when I got the engine to try to help with freeing it up, which is the red fluid in the #2 cylinder. Pistons #1, #5, and #6 all came out pretty easily, I'm soaking the others in ATF, Diesel, and PB blaster and am going to try removing them tomorrow.

I’m back with some progress and updates! As per the chassis, I’ve completely redone the frame, steering, and suspension. I’ve been focused on bodywork in the meantime (I hate bodywork).

As per the driveline, seems I’ve stumbled my way into owning 4 slants (because I guess my pile of parts isn’t big enough…), 3 of which being the John Deere agricultural variants and 1 from a 1973 D100. I had paid $400 for my 1st Deere engine (seized), I got the truck engine from a parts truck I traded a 318 for (seized), and I just picked up the other 2 Deere engines for a combined $400 (1 seized, 1 free). I also scored a truck A-833 OD!

The Deere engines are only rated at 55 horsepower, so I’m wondering if the deck height and/or cam profile differs from automotive applications. The governed carburetor may be more to blame than anything, but I’ll be able to measure the deck and cam against the automotive engine to make sure.

The free engine has a forged crank, so I’m planning on using that as the base for the build. One other Deere engine has the peanut plug head, which I’ll be using. The truck engine is the donor for anything needed for automotive adaptation (alternator, thermostat housing, flywheel, carburetor, oil pan, etc are all different on Ag motors). Since the Deere engines were governed and only made 55 hp, I’m assuming that they’ll be in good health and won’t need any machining.

I realized that the initial plan for my slant was too ambitious for me, the only things of note that I’m hoping to do on this engine are to raise the compression ratio and maybe find a 2 barrel manifold for it. I’ll drive it then decide if I want a cam, dual exhaust, and/or better intake manifold. Assuming the deck height is standard, is there enough material to remove on the head to raise the compression ratio or will the block and head need to be milled?

This is not correct; see here.

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Too many people who were born on third base actually believe they've hit a triple.

I would highly recommend no less than a 3.55 rear with that OD. A 2.94 will be terrible in my opinion. That is of course unless you can drive downhill everywhere you go!

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2 Mopars come with Spark plug tubes. One is a world class, racing machine. The other is a 426 CI. boat anchor!

12.70 @ 104.6

Have you yet attempted to put an engine into the engine bay on that Fargo? I ask, because I seem to recall that the slant has offset engine mounting points as compared to an LA small block. You may have to do some fabrication.

Roger

That's taken care of in the motor mounts. The metal part that actually bolts to the block not the rubber parts.

70s Dodge truck and van K-frames are like the early A body K frames- same frame for slant and v-8 applications. Ony diference is the motor mounts.

I agree that an overdrive trans should be paired with 3.55 rear gears or numerically higher.

https://pami.ca/app/uploads/2026/05/52.PDF View page 8 of the operator's guide for the manufacturer's power rating (55hp). This engine is equipped with a tiny carburetor that's controlled by a governor (likely set below peak hp. Additionally, the head measured at 62cc, iirc the regular slant was rated at 54cc. I wouldn't be surprised if that's within regular slant 6 production tolerances though

I'm not entirely sure what gears are currently in the 8-3/4 rear, but a 3.55 set is now the plan. I'll likely try out the current gearing, discover that it's a 2.7 and miserable To drive, then swap out to a 3.55

I've done probably just about enough babbling about real vs. fictional horsepower ratings of the Slant-6 here and here. This "55 horsepower" thing is some mix of misinformation from the factory (misprinted once, repeated forever), a nonstandard rating protocol, and/or, as you say, a very small carburetor (but it's nowhere near small enough to account for the entire difference).
Yep, your surmising is correct: passenger car/truck Slant-6 combustion chamber volume is all over the place (there was no 'rating').

Low-compression Slant-6s did exist for markets with low-octane gasoline, but this was done with special pistons.

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Too many people who were born on third base actually believe they've hit a triple.

And, really, 3.55 are the absolute lowest (numerically) gears I would put behind an overdrive transmission, especially in a truck. i have owned several vehicles (heavy vehicles) with 3.55 rear gears, an overdrive transmission, and a smallblock v-8. While turning 1700 RPM while doing 70 MPH is fine on flat roads or downhill, going uphill or towing is a much different matter, even with 3.55 gears.

I would prefer 3.9 or even above 4 rear gears in a truck with overdrive, especially if the truck is going to be used in hilly areas or be used as a truck to haul things. With 3.55 rear gears the engine usually doesn't get in its most efficient/powerful RPM range in overdrive.

Based on the 1972 sales brochure, your rear axle gear ratios could be 2.94, 3.2 (standard), 3.55, or 3.9. Anti-spine was available only in 3.2, 3.55, and 3.9 ratios, but who knows what has been done to the truck in the last 54 years.