The 5.2L V8 was not a bad engine at all, for its day. However, like the others said above, it will be a severe headache just to get running, let alone everything else operating correctly. In effect, what you are doing is dropping the newer 2008 plastic shell and seats onto 1996 or 1998 guts.

If you are dead set on doing it, I advise this: take care of every potential issue on that 5.2L V8 before you drop it in. It will cost you more right now, but it will save you money and future headaches in the long run. Much easier to work on the engine while it is out.

Just to get you started:

1. Fix the plenum gasket. The 3.9L V6/5.2L V8/5.9L V8 engines all had this issue. Chrysler used slightly too long of bolts on the bottom of the intake manifold, so the plate there (commonly called "plenum plate" or simply "plenum") usually ends up breaking its seal. This allows oil into the intake manifold. Best case scenario, this results in decreased power/gas mileage. Worst case (most experience the worst eventually), your engine "pings" (predetonation) and your catalytic converter fails. To replace the plate with an aluminum one, new bolts, and a new gasket, you're talking around $100 or less. Some opt to replace the whole intake manifold with a single-piece performance unit, but that is much more costly.

2. Replace the heads, or at least have them thoroughly checked by a shop. The stock units were prone to cracking, especially if they were ever even close to overheated.

3. Check compression in all cylinders. Make sure they are up to spec.

4. Check out the 2nd Gen Ram, 1st Gen Dakota, and 2nd Gen Dakota sections. They will have more information on common 5.2 issues.

Definitely stick with the manual transmission for the older engines. The automatic transmissions for the 3.9/5.2/5.9 were so-so at their best times. A temperamental transmission is one reason why I traded my 2001 Ram in for my current Dakota.

 

If I was looking at this for myself, without much research, here's what I would estimate to be the scope of work (still leaving you with a 10 year old truck).

• I would assume that the motor and transmission mounts would be different, so I'd be looking to cut some mounts of the wreck and weld them in place on the 08.
• I'd take the engine, transmission, and transfer case from the 98 and move the 08.
• I'd get both driveshafts resized and add the CSD joint to the front shaft (make sure both shafts are balanced after re sizing).
• I'd take the entire engine bay harness, including computer (there might be a security module in that layout, and that might be in the cabin, so that wiring would also need to be moved and spliced in so the 98 computer will recognize a valid configuration), and splice that into the cabin harness. I would want the wiring diagrams for both years and then some things on the newer truck that relied on the computer to activate, won't work with the 98 computer, so you'd need to modify the control of these to be manual. Test this as you go to ensure you have things wired properly.
• If the 98 key is chipped, you'll need to find where the chip sensor is and move that to the 08 (along with the entire key switch assembly).
• There will probably be some other things that will need to be moved and mounts for this stuff fabricated, but you'll at least have both trucks to work from.

 

This is so much more work that even my diesel swap.
The 08 is all CAN communication between the ECM, FCM and all the 5? subassemblies like ABS, Air bags, gauge cluster, radio and I think I'm missing something.
At least with my swap I was not depending on getting the ECM to fire up the engine.
Its basically there to provide a few key inputs to the FCM which runs most of the other systems.
In 08 they changed the ECM's to a 64 bit from the previous 32 bit so and older ECM wont work in the 08 trucks.
Also all the CAN nodes are VIN coded so if you replace one of them with a module out of another vehicle you will get an error code since the FCM wont recognize it. There are a couple of companies who can re vin code the module for you.

I have done MANY engine swaps in the last 35 years and these new vehicles with CAN are almost impossible to make happy after you touch any part of the drive system unless you can hack the ECM / FCM and reprogram. I have not found anyone who could do that for me other than a few guys playing with a few setting in the ECM for performance.
Swapping in an 08 4.7 would be the best chance at success but still not an easy swap. They did not offer a standard trans with the 4.7 in 08 so no ECM exists for this combination.
A good diagnostic software package like Auto Engenuity is a must so you can see what sensors you still need to get working to make the system happy.

BFN
Randy

 

This is the same as what I had found from my own research. I was just kind of hoping it would work anyway somehow. So the best bet is to go with the 4.7? That is still doable, just not as available as the older models around here. So with a 4.7 is there a way to put a standard trans in it or no? I would really hate to give that part up. I love my truck but I miss driving with a clutch.
I am doing the build in my spare time. I have a two week old son so I don't have much free time, or cash but I have a few grand to put into this.
I am also curious about the aftermarket for the 4.7? I had planned on a few upgrades to my current 3.7, but figured I would get more bang for my buck starting out with a larger engine then getting upgrades. I am leaning more to better mpg's than drag racing, but I would not mind turning a few heads either. lol any and all input is greatly appreciated.

 

There are also three different versions of the 4.7 to consider. The pre-2008 4.7L V8 came in two forms, regular and high output. The high output is very hard to find, but is a little stronger built and more power/torque than the regular version. Only "bad" thing is that it was designed to run on 91-92 octane fuel and not the cheaper stuff. However, those two can be had with a manual.

My personal favorite is the 2008+ 4.7L, however. A bit more like the HEMI, dual spark plugs per cylinder and all, more power/torque than even the HO previous version, and on regular 87 octane fuel at that. However, not sure you could easily get a manual mated to it.

Pre-2007 regular 4.7: 230 HP, 290 lb-ft
Pre-2007 HO 4.7: 250 HP, 300 lb-ft
2008+ 4.7: 302 HP, 329 lb-ft

 

So I have decided to trade my truck for a '08 Dakota that has the 4.7 in it already. I found one not far away that will almost be an even swap. It has 60,000 miles on it, compared to my 41,000 on my 3.7, Still fairly young I think. I plan on having to do some light engine work when I add on the aftermarket parts if needed. So let the real games begin, with higher mpg's as the greatest goal in mind what would you guys suggest I work on first? I have over sized tires with custom rims to compensate for as well on the mpg's, I have had them since my first Dakota, I don't really want to part with them.

 

Superchips tuner should be your first purchase. Best bang for your buck.

If you do a search of the forum here, you'll find plenty of other threads with other suggestions as well.

 

Good call my friend. Probably the easiest way to do that motor swap. The newer 4.7 has so much more power than the old 5.2, and you won't even have to get your hands dirty, yet.

 

Thank you all for your advice and suggestions. I brought my new toy home and am about to start reinstalling my interior lights that I had in my old truck. I had replaced the overhead dome and map lights with LED's, and added strip lights under the dash and seats. I had a really hard time finding a good diy on the strip light install when I had done it in my old truck, so I think I will see if I can make one for the next guy when I redo it.