A833 OD 340 4x4?

While the 340 can be fun,
the 360 will have a whole big buncha more low-rpm grunt.
While at 3000 pounds the 340 would be more than up to it,
the 360 will be better at 4000.

400 meters is a very long way .
a 340 done up for that will NOT like the 3+1,A833.
Even the 360 at 4000 pounds will have trouble with that trans, with a cam of more than [email protected]
It's not the getting off the line that is the problem; rather, it's the 1.67 second gear that sucks.
With a 340;
Let's say you run 28" tires. And low gear is 3.09 so you want a starter of say 10 or 11 to 1. And that means you can run 3.55s. Which is a great starter gear; not too deep, and not too shallow, but perfect.
But with 3.55s, 65= 2000 rpm, so if fuel economy is on the table, this is borderline too low for the 230* cam your 340 is gonna want. With the 230 cam 3.91s is what she wants to cruise with. But 3.91s make a starter gear of 12.08, which means that the rpm is gonna climb very rapidly in first gear; annoyingly rapidly. And Bam! you will be in Second gear... typically shifting at say 3200/ 22mph(3.91s). But at 22 mph in Second the Rs drop to 1720rpm, so the 340 is way out of it's element, as in total lack of torque. But you say com'on, it's got 3.91s why is it so doggy?
Ok, the 340 with a 230* cam to satisfy your rapid transit to 400 meters, is gonna want to be up at around 3700 before she will deliver some power. In Second gear (1.67 x 3.91), this will be, wait for it..... 47 mph. So no matter at what rpm you outshift First, your 340 is gonna have to buzz up to ~4700 to find some scoot; and that's with 3.91s! To get 47 mph in First gear requires 6800 rpm. If you are running a 230*cam, it will peak around 5200 and you will shift it at around 5500, and 5500 with 3.91s is about 38 mph. On the 1-2 shift, the Rs will fall to 2980, again waaaay into the marshmallow zone. So now the 340 has to struggle up to 3700/47 mph. But 5500 in Second is 70mph. On the 2-3 shift at 70mph, the Rs will fall to......3300; let the struggle begin again. If your 340 equipped 88Dakota can hit 90 at 400M, that will be 4200, way down the power-curve.
So, like I said, Second gear is the problem. It's too far from first, and just as bad on the 2-3 shift. You can put Second Gear where ever you want with rear gearing, but that just messes everything else up.
Check this out. A good place for a streeter to be geared is 2800@32mph, in Second Gear. This is comfortable to cruise around on, and at the downshift into first, the truck will rocket forward.
With 3+1 box, this will require ~4.30 rear gear, and on the downshift, the Rs will jump from 2800 to 5200 right on peak power................... but you got only 300rpm to 34mph and then it's back into Second; that really sucks. Now;
With the Commando box, 2800@32 mph as before, will require a 3.80 gear, rounds to 3.73s, so 32 will be 2750, and on the downshift into First, the Rs will climb to 4420 (instead of 5200) and you can wind that up all the way to 5500@40mph, BadaBoom!
What about the 360?
Well the picture is a lil brighter. For the same 400Meter performance, you can run one size smaller cam. This will get you a double-whammy of more low-rpm power; Firstly the 360 has more by virtue of it's stroke, and secondly, the smaller cam can deliver more.
So now, maybe the torque comes in around 3400/43 mph.
But hang on, why are we still running 3.91s? The 223*cammed 360 does not need nor want them. 3.7s will do just fine. Even 3.55s.
So with 3.55s, 3400 will be , wait for it......48 mph. Chit with a capital-C.
I'm telling ya that 3+1 box is terrible for a hot SBM
I made that 3+1box work by running alloy heads and cranking the pressure to 185 psi. And it still sucked in my 367 with a [email protected] cam, and worse with the [email protected] cam.

My tip; Run the early Commando 4-speed and forget overdrive. It has the perfect Second Gear, and Third is right there beside it; and the 360 can easily pull the 3.09 gear with 3.55s. I'll bet the 340 will only be a lil softer on take off, running the same cam and same cylinder pressure.
Ok, now 3400rpm with the Commando, in Second gear, with 3.55s, is 41mph..... but, first gear will get you to 44mph at 5800, so BadaBOOM! The 1-2 shift at 3200(First), now gets you 24mph at 1990rpm, going into Second, that's 2mph faster and 270more rpm with 3.55s now, versus 3.91s with the 3+1 !! that's a mighty big win.

Here are the A833ratios, (with the 1 x23 input);
3.09-1.67-1.00-.73od ( 3+1 misery)
3.09-1.92-1.40-1.00 (Commando)
2.66-1.92-1.40-1.00 (standard box)
2.47-1.77-1.34-1.00 (the close-ratio T/A box.)
Now, plug in some rear gears, into this formula, and see what it takes to make you happy;

MPH= (RPM x TC)/( 1056 xR1 x R2)

Where TC is Tire Circumference which is; diameter x 3.1416
R1 is trans ratio
R2 is rear gear ratio
1056 is a constant that converts the resulting product into a simple speed number.

>Which engine you chose depends on how low a rear gear you are willing to run, how much tire-spinning you want to do, and how much you value low-rpm running on the hiway. As for the 400meters, either engine will get you there,in the same ballpark, depending on how you set it up.
>The 4X4 will suck some power too, so another reason to go 360.
>IDK what your gas quality is like in Costa Rica, nor at what altitude you are running, so that, if you cannot run high-pressure, points to the 360 again.
>Alloy heads will let you run 87E10 to at least 185psi in my experience, with full-timing.
__________________ opinion coming_____________
Don't buy into the 340 better than 360 hype; that is just not true. Combo for combo, the 360 will do anything a 340 can, but with more low-end grunt.
I bored mine out to 4.04 so now its same as a 340 except has a longer stroke. And I cranked the Scr up to 11/1, better than any factory 340 ever was; and no factory 340 ever pumped 185 psi. So my 367 is like a 340 on steroids, just what you Dakota needs.
185psi with a 223* cam is a flippin' tractor at low rpm, a powerhouse thru the midrange, and I set mine up to rev to 7200... jus cuz I like to hear it screaming.
My rig is 3650 with me in it, and she likes 3.55s, but likes 3.23s almost as much.

BTW;
that overdrive is "fragile" to say the least. I blew two of them up, just by accidentally slamming the trans into "fourth" which is easy to do with certain bigger number rear gears. And when it shatters it goes everywhere, including down between other gears and wipes the whole trans out.

Ok time to cut it short,lol