Well, this is a very complicated set of questions. Not hard to answer, just long answers, lots of little things, and details, etc. This is helpful if you want to make your own 4wd using a truck frame. It seems that 1973 - 1987 GM trucks are a common chassis to base your new creation on. Parts are readily available, and common, and don't forget cheap! Keep in mind that this information applies to any body swap involving putting a body on a chassis it was not originally manufactured for.
1. First and foremost, you want you new ride to be reliable. You must always keep that in mind.
2. Chances are, you don't want to spend too much cash, so you naturally keep that in mind, but still remembering # 1.
3. You want your new ride to be mechanically strong, and sound.
4. You have to decide what your goal is in doing this swap. Show vehicle, show n go? All go? Stock looking for the most part? Monster truck wanna be? You still must keep # 1 in mind.
5. Decide exactly what you are willing to modify, when doing this swap. Steering? Suspension? Shorten the chassis? Lengthen the chassis? Shorten the body? Lengthen the body? Make custom body mounts? Custom fuel tank?
6. Look for a swap that suits your skills. There are many ways to do any given swap, to achieve the desired results. Many are easy compared to others. It all depends on how radical you want to get.
7. Get out your note pad, and a good tape measure. Get a friend to help take measurements, to see how difficult this project will be. Measure both vehicles. Things to note and graph are wheel bases of the 2 vehicles, body mount locations, frame widths, frame lengths, overall "rises" and "dips" in the chassis', engine compartment clearances, fuel tank locations, etc.
8. Choose the hybrid you will be building, and gather the necessary parts (body, chassis, etc) and supplies for the project.
9. Look for every possible snag, detail, or anything that may make you have serious second thoughts about your hybrid project. If you end up not finishing it, it will be a worthless pile of parts for the most part. Especially if you alter parts to make them fit, then try to sell them.
10. If you still think you can do it, then it's time to get moving!
11. If you can get your hands on a Factory Service Manual for each of the vehicles you are using to do the swap. then it will make the swap much easier. Many dimensions are in the manuals, saving you time, and ensuring accuracy. Ebay is a good place to get manuals.
I feel the most important factor of swapping bodies, is the wheel base of the two vehicles. It should be as close to the same as possible. Nothing looks worse in my opinion than a monster whatever, with the tires not centered in the wheel wells. This is very noticeable, and makes the swap look shabby overall. Often it's difficult to find two vehicles that are the same. Especially if you are set on a particular swap. You want to "make it work". This is always possible. What's involved, may stop you from trying to do it. A lack of skills, tools, and knowledge most of the time. You also need a place to tear apart the two vehicles, and work on this project. It takes more space than you think you'll need. When all is said and done, it is usually observed much more was said, than done. Parts will be everywhere. You'll have leftover and unnecessary parts to scrap, that you can't put in the trash, or take to the dump.
When the wheel bases are that close, it goes much easier. If yours are very far off, say 12" or more, you might want to consider another chassis for the swap. If not, you might consider adding a section to the body, to compensate. You are best off leaving the chassis exactly as it was designed. I do not recommend lengthening, or shortening a frame in the center, by adding or removing sections. Look at it this way, the frame (chassis) is like the foundation of a house. It holds the house together. If you want
to remodel, you alter the walls, and floors, not the foundation. You may add to the foundation, but you wouldn't add a section in the center to make it longer, or remove a section to shorten it. The chassis is the "foundation" of your new ride. The body, is the "house".
If you are swapping a pick up onto your chassis, it's easy to add or remove a section of the bed. Anything else, adding or removing sections gets tricky, and takes skills and tools to do the job properly, and safely. Most backyard do it yourselfers like us don't have those skills, though I'm sure some of you reading this do have the skills and means.
You basically want to leave the chassis in it's original condition, structurally speaking. You can build the custom body mounts you need to do the swap off the chassis, or off the body, sometimes both, and meet in the middle of a "long span".
The body mounts of both vehicles, and the "perches" for the body mounts on the two vehicles' chassis' are important. How different they are, will decide how difficult your swap will be. You will have to make custom body mounts from scratch, or adapt ones from another application. Some of the mounts may line up, or other options, other than the original mounting locations may exist too. I do not recommend stacking one frame on top of another. At least not 2 identical frames, like some of the older monster trucks used to do.
Every swap is different, so it is extremely hard for me to be as specific as I'd like.
Again, the main areas of concern in the beginning, are:
1. Wheel bases of the two candidates for the swap.
2. Chassis lengths.
3. Body mount locations.
4. What you want to accomplish (Finished Product)
5. Will it be street legal?
Reliability is important. This is why you would want to upgrade a points type ignition system to HEI. Unless there is tons of mud nearby, and your state doesn't have stringent vehicle safety inspection laws, you should stay with tires 35" or shorter. Again, practicality plays a big part here.
For instance, here in New Jersey, all vehicles have to pass an annual (now bi-annual) state safety inspection. Trucks, depending on their physical state, may have to undergo special testing. The inspector determines if the truck is lifted more than 4" over stock. If it is, they can reject it, and send it for a stability test. In a way, this is good, as it keeps lifted trucks safe. Eliminates those that have blocks on the front axle, dangerous steering, etc. They have taken it a little far though.
For example, my 77 Chevy must go through the stability test / safety inspection. I have a problem with this. The reason is that I parked along side a buddy's new Ford F-350. My truck is less than an inch taller than his. His is stock, mine far from it. My truck's stock tire size is about 31" tall. I have 36's on it (had 35's when next to the Ford), have a 3" body lift, and a 4" suspension lift. That works out to 11" over stock. That's why I now have to go for a stability test. I know I will pass, because my truck has a long wheelbase, and the rims have a better backspacing, to give the truck a wider track width. The larger tires and wheels add more unsprung weight than when the truck was stock. My truck is very stable.
Additionally, my states governor just made a new law about tire sizes.
For a complete list of all the requirements lifted vehicles must comply with in NJ, go here. Current NJ Lift Laws David has posted the letter he received from the state DMV.
You sure don't want to build a truck, only to find out you can never legally register it. You must consider every factor, and every aspect of any given swap long before you begin. Don't rush, take your time. You'll be amazed at what is possible.
Truck Restoration Parts - Here
- This is the place the Pro's go. Too much to list here.