I just purchased a 96 Dodge SLT 3.7 V6 sad ext cab.
I'm planning on doing a slam airbag suspension and I'd like to swap in a 5.7 V8 and A/T from a Charger.

Is this a relatively straight forward swap?
Will the 5.7 with an A/T fit?
What is the preferred year of engine and transmission that I should be seeking?
I'm assuming I need all of the 5.7 computers, emission crud, and harness?
How do I go about swapping harnesses?

Any & All subject matter assistance is greatly appreciated!

Thanks, Mike

 

Nothing straightforward about it. Everything is different. From engine/trans mounts, to electronics, to how the instruments work. Nothing is the same.

That said, it will be easier than if your truck were 98 or newer......

Will it fit? Probably. Will it be easy? Nope. Better have a well equipped shop, and some good fab skills to make it happen. (or, friends with said skills. That works too.)

 

*dry* You may want to check things.

The 3.7 wasn't offered until 2004.

If it's a 1996, it's a 3.9, and you'd find it easier to go Magnum 5.2 or 5.9 (318 or 360).

The 5.2 was a factory option in the 1996; the 5.9 bolts right up where the 5.2 does given a few small caveats (mostly the 5.9 is externally balanced, the 5.2 internally; use the right harmonic dampener/balancer and the right flywheel/flexplate and torque converter combo, and you're good).

If, however, it has a 3.7, then it's not a 1996.

OTGH - if you just MUST go 5.7 Hemi, check out the parts that Holley now has for a almost bolt in job.

RwP

 

Thanks RalphP!
You provided a lot of great info. Obviously, I'm new to this arena and I don't know what I don't know.
It looks like a 5.2 might be the best (least expensive) option for me here. Perhaps I should get an older 5.2 and build a 383 stroker.
Any idea what a rough parts cost is - just ball park would be awesome.
I'm hoping to be in the 400 HP range with reliability.
I'm not going to be racing - just an occasional burn-out or two...

I found a parts truck with a 5.2 for $500 but it has 200K on it. I could use a few body panels but will need to rebuild the engine and trans.

Your feedback and expertise is greatly appreciated!

Mike

 

The 5.9's are out in there in plenty as well. You would just need to add the additional two injector circuits to the harness, (or, swap the harness....) and get the PCM flashed for a V-8. (whichever size you decide to go with.

Building a stroker ain't cheap. Just buying parts, paying for machine work, you are probably figuring in the neighborhood of 4 to 5K. Not including the price of the motor itself. But, if you are going to do that much work to it, really doesn't matter how many miles are on the donor, so long as it still runs, and doesn't make any rude noises.

Next question becomes, what trans does it have in it currently? Probably not something that would last long behind a reasonable powerful V-8. (considering I don't think the V-6 even made it to 200 HP......) Do you want auto, or manual?

 

The donor truck I found has a 5.2 and auto trans in it. I prefer an A/T for this application.
The truck that I have also has an A/T but I agree it's coupled with the V6 so that won't be a good option.

Next decision is to go for the 5.2 or the 5.9!?!

Again, the donor truck has a 5.2 with A/T and a few body panels that would be useful.

Your thoughts...?

Thanks, Mike

 

On you man. It's your truck, build it how you want it, with whatever parts you can scrounge. Personally, I prefer the 5.9, as it is essentially the same motor as the 5.2, just, more cubes. So far as I know though, the 5.9 never came in the Dakotas.... Whatever performance parts you toss at it, the 5.9 will give you more bang for the buck. Still a lot of support out there for both motors though.

What trans does your potential donor have in it? I think some of them came with the 42, or 44RE..... neither of which I think would be stout enough for what you have in mind. You REALLY want the 46RE. (and it has to be 96 or 97 as well, so you have the provision for the VSS on the tailshaft housing.) There are a LOT of upgrade options for the 46RE trans.

So, if the potential donor actually has the 46RE in it, maybe pick it up, strip the parts you want off of it, sell the rest, and buy a 5.9 that you can build?

Also keep in mind, that if you stray too far from stock, you will also need a custom tune to run the engine. Another expense.

 

The 5.2 Magnum and 5.9 Magnum share the oil pan and pickup tubes; so that's good from the donor.

See if you can find a 5.9 Magnum.

Even if you stroke, it becomes a 408ci and presto, extra cubes.

It really, REALLY depends on your end game for what to do with the truck. "I want 400 HP" doesn't say much; do you want 400HP at 25,000 RPM with 15 lb/ft of torque? Or 200 HP at 2,000 RPM with 1,000 lb/ft of torque? (Pulling numbers out of the air here). It makes a difference.

If it's strictly for show, anything can be done, all it takes is time and money.

I myself? Would start with a 5.9 ("There's no replacement for displacement". And for those that scream "Power Adder!!!" be it turbo, super, or spray; well, duh. But if it doubles the HP, doubling 400 beats doubling 200!)

There's actually a few articles on Moter Trend (from Hot Rod and older Car Craft articles) that describe building up a 400 to 600 HP Magnum ... 318 Engine Build - A Parts Book 400HP 318 (motortrend.com) for instance. However, that one is an LA, so you'd need the proper Magnum parts. And by starting with a 5.9 you get more. See 5.9L Magnum Engine - Make Mine A 5.9 (motortrend.com)

OTGH, you already HAVE the 5.2 ... can start with that and go on.

Transmissions - the 42RH can be build easily to 44RH specs; and can be beefed up past that. The stiffer 1st gear (42RH gears are 2.74, 1.54, 1, and .69; 46RH are 2.45, 1.45, 1, and .69 to 1 respectively) can help the truck launch a bit more given you have the traction to put the power to the ground. The 46RH, OTOH, is descended from the venerable A727 - the most rugged automatic Mopar ever made. (There are a few more that they've used that were stiffer, but they weren't Mopars but Aisins and others that Mother Mopar bought ... )

Your BIGGEST problem is that the older fave for inexpensive upgrade cylinder heads, the EngineQuests, are ... not what they were two years ago. They moved to a Chinese foundry and aren't the quality level they used to be. Le sigh.

Do this first - rebuild the suspension and work on the brakes.

If you're going for that HP level, find an Explorer with the 8.8 and TrakLok limited slip; rebuild that, and have the spring mounts and shock mounts put on to match the Dakota. Use that to pick up the 5x4.5 pattern and disc brakes.

Convert to 87-90 front hubs (I presume 2WD) which also has the 5x4.5 pattern; the rear will fit Mustang wheels no huhu, the front will have slightly larger center bores so your choice of wheels becomes a bit more limited. Not impossible; there's several 5x4.5 Mopar vehicles out there (I'm running Jeep Cherokee wheels on my 1988!) so you've got some choices for better wheels and tires.

Use poly bushings and GOOD ball joints (Holley bought out Pro-Forged; they are still hefty well made ball joints. They didn't bring over the outer tie rods for the rack and pinions, alas; those, bronze got some AC-Delco Pro Grades. ACDs were OOS when I went to order some since my rack is wearing out; I bought some Mevotech Supreme outer tie rods. They look and feel good, threads are clean cut, and the dust cap is captivated so it won't flip around. YMMV though) when you rebuild the front suspension.

You may have fun with the bags; you're talking about a full custom suspension there. If you're going that far, pick up some spindles that can take some good disc brakes front and a core rear-end that works well with discs. If you're putting 400+HP to the ground, you want brakes better than "Well, it will finally stop!" a 125HP truck ...

 

Did you mention ACDelco bought up Raybestos? And are the current ACDelco balljoints formerly Raybestos? Some or all?

I just bought some ACD Pro control arms for the wife’s Jeep. Comes with bushings n balljoints installed. Was surprised when I opened the box and saw the bjs were greaseable. The spec said they weren’t. Happy about that. I’ll add I have yet to see anything cheap about any ACD Pro part I have bought. Even the R&P bellows are quality. But, in the end time will tell.

I checked with Proforged (Holley) first but they don’t make parts for the wife’s Jeep save maybe the inner tie rod. I went with ACD Pro. Proforged seems to have a limited offering. Maybe Holley will run with it.

 

Raybestos, and ACDelco, were both using Spicer Pro for their professional grade.

They're still using the same parts, but Raybestos has gotten out of suspension parts as far as I know.

I've got nothing against ACD Pro! I was mentioning ProForged because before Holley bought them, they were 'The Little Guy Who Done Did Good' Even now, I'll use them if I have a choice first.

RwP