New motor, Old truck

[o3shortbed]

just the other day my "wife" totaled my 03 chevy. i was wonderin if i could put the 5.3L and 4L60 in a 67-72 chevy. i like those style trucks and LOVE the EFI of the newer motor. i looked on painless but could only find fuel management kits. i would need something to control the motor and tranny. i dont want the EMC to put me in limp home mode if i put it in the older truck and dont have something hooked up right. any advice you guys have would be nice.

[87c10slammer]

good luck im only goin 2 years apart and im told its hard as ****. i really doubt that you could get that to work but i would pay to see it

[rebelchevy]

i helped a friend put a 99 5.7 in his 90 and didnt have any problems with it. we took the complete harness from the 99 so it was basicly a plug and play. i dont know exactly how much changed in those 4 years so.

[Rick Hindmon]

o3shortbed,
I have seen a wiring harness for this conversion, I just don't remember where but I will look for it and let you know who has it.

[75K30]

I have done this exact swap onmore than one occasion.
Few things that willhold you up, or make this as easy as pie to do.
You would be wasting your time trying to use an aftermarket harness and wiring, after all everything that you need is right there. If you look at the main wiring harness on the engine you will see that it is easily removed from the electrical control center.
You will also notice that the power distribution inside of the truck (at the fuse box) is also very easy to remove and disassemble. Know that the wiring harness only reaches certain portions of the truck, and most tof the connectors are unique, so there is not much of a chance of getting things confused.
Since the speed sensing is done at the transmission, you might as well use the trans too.
I removed the entire wiring harness from the donor wrecked truck, as well as every stich of wiring from the old truck. I removed everything right down to the tailights and bulbs.
This is where things get cool:
Once everything is removed, (both harnesses) you can lay out the new harness and get it ready to install. You then need to cut a hole in the firewall large enough to fit all of the new electrical through. I used a 4.75 (121mm) hole saw to make my hole. This was the right size to use the factory grommet for a nice water tight seal. This will make the connection between the inside and the engine compartment. You will be left with a long tail that will run parrallel to the frame on the driver side, and this will be for the fuel pump, sending unit, and tail light assemblies. Run this along the frame, and complete terminations as necessary. Believe it or not, your tail lights are easily modified to accept all of the late model bulbs. You will now have individual bulbs for turn signals, and running lights, but under a common lense, it will look original.
Once you have the basic harness installed, you can now start connecting things like the new fuse box, and all of the electrical control connections. You will have two blue plugs that used to supply power to the individual doors, and if you leave these disconnected, you will never recieve a door ajar indicator, nor will that annoying dinging noise ever sound. You security system will never work either, and the truck will start with the door open, since it will think that the dorrs are always closed, so keep this in mind.
Next, drop the engine and trans in, and make up your exhaust, trying to keep the factory cats and you must maintain the 02 sensors. To make things real simple trying to figure out how to use tha late model tank is a plus, since the fuel pump and return is already plumbed. You can even use the existing fuel lines like I have done. These tanks are pretty tall, and thay will stick below the frame a little, but in a 2wd truck not a big deal.
Next order of business is simply connecting all of the late model engine connectors to the proper place, and than the fun begins. You have to figure out how you are going to get it started. I would use the steering column from the late model truck, since the gear selector is already incorperated into it, and so is the key. This will make the intergration much easier and eliminate the headaches involved with trying to get the wipers, cruise control, ignition and gear selection.
You must re-wire the brake light switch, and jumper out the terminals that lock the shift lever until the brake pedal is depressed. This can be a little tricky, but with a multi meter, very easy to figure out. This is located in a square plastic box that attaches to the factory brake pedal.
After this, the truck should start, and run just as it did when it was in the ther truck. I would even use the radiator, and all of the stuff that is still good from the donor truck.
Other little tricks are wiring the headlights using ths late model harness. This is interesting because the newer truck has 4 individual lights, and the old truck only has 2. Wire the late model harness to the early headlight, and the highbeams are always on, and you willnot be able to shut them off.
You will need a pair of relays to make a form "c" contact that will energize when the high beams are on. This will open the contact for the low beams when the high beams are activated, and you will have high and low beams, and your indicator will be active provided you use the factory gauges. The gauges are a one connector system, and pretty easy to incorperate into your dash.
Without getting too in depth, I tried to cover some of the fun highlights of this swap. It can be a challenge, but is fun, and well worth your effort. These little engines run very well, and you will suprise yourself with how much fun this swap can be.
You will have bragging rights over the entire neighborhood, and car guys from all around.
Please let me know if I can provide additional info. As I have stated, I have performed this on many occasions, and it get easier each time.
Good Luck.

75

[gmctrucks]

75K30 hit it right on the nose can't go wrong in doing what he says. This member is one smart cookie.

[o3shortbed]

hummmm sounds like a lot of fun. thanks for all the info 75 the donor truck was hit in the rear so the radiator and stuff is still good. i cant wait to get this started. another question. my o3 has keyless entry can i hook the powerdoor locks to some solinoids to pop open the doors by the remote? that'd be cool too

[75K30]

Yes, you can, but this becomes a little more interesting. You have all the power distribution right at the blue plugs that are located behind the kick panels. You can alsi hook up the power widows, and mirrors if you like. You may even go a step further and remove the power seats, overhead console, and even the auto dimming rear view mirror with compass if you have that. All of the wiring will have to come out, and you will have to also wire some door switches so the vehicle knows if the doors are open, or you will get that ding ding noics all of the time, and the security system will not work.
I have seen the entire dash used in early trucks. While this is quite a bit of work, it can be done. You get the idea.
You will have to fab up some engine mounts, but again this is pretty easy. Last time I used the stock silverado front crossmember, and split it in half, I then cut the ends off, and stood them up and bolted them to the LS engine mounts. Once the engine went in, I was able to get the correct angle and bolt these to the frame. It was as easy as that. Now I was able to use factory style rubber mounts.
You will also enjoy using the original radiator and trans cooler etc. These come off easily with a few clips, and are real close to the same dimension as the old truck. By all means use the radiator shroud and everyting you can.
That package comes out much easier than it looks, and will look real clean when complete.

[o3shortbed]

i figured id hafta fab up some mounts and the drive line. now all i need is an old truck