I am in the planning stage of rebuilding my 71. I would like to replace the engine / transmission / transfer case with something newer. I would like to have a V8 fuel injected with an automatic transmission. With all that being said I am looking for some opinion on what would be the best and easiest swap. I would appreciate any ideas. Thanks.

Todd (mudpuppy)

I think you're likely to get a wide variety of responses to that question. Perhaps the best thing(s) you can tell us to help narrow it down are: what's your goal with the Bronco following the rebuild? Daily driver? Trail truck? Etc.

I would like it to be a daily driver that I can do a decent amount of 4 wheeling with. Nothing that extreme. The bronco was my fathers before he passed away. I want to do the build with my boys as a tribute to the grandfather. Not sure if that answered any questions or not. In the end I want something I can pass down and be proud of.

You've got a couple of options:

1. Fuel inject your current engine. Not sure why you want to upgrade, but going to a later block would give you some gains. That said, this is probably the easiest path to follow.
2. 5.0 out of a '96ish Explorer. If you get it complete, it'll get you a serpentine upgrade at the same time. I'll drop right in and wire up with about the same level of difficulty as converting your existing engine. It'll be a roller block which with give you some HP and torque gains. The only down side is having to deal with a potentially unknown history.
3. EFI 5.8L. '94 or later out of a truck or van will get you a roller block. More power, more torque, potentially slightly worse mileage if that matters. It's a little more to source all the parts, as the truck intake doesn't fit under the EB hood. You can get an adapter from BC broncos to run the Mustang upper withe truck lower or source a lower from a Ford Lightning. The latter is the better way to go, but they're expensive. Wiring and such is the same as the other two options.

I'll leave the transmission options to others. I'm a little biased towards the NP435, and I doubt that'll fit what you're looking for.

Justin hit the high points of the modern engine options.

the most common swap is a 5.0l fuel injected engine with a C4 auto, with the parts already in your rig it is as close to a bolt up swap as you will find, very driver friendly and it has been done so many times by so many folks here in the club there should be few if any surprises. Same holds true for the 5.8L swap, tho it is a bit more work.

Other trans options are an AOD or EAOD which will give you another gear, essentially a C4 with over drive without to many issues. The EAOD will be electronic control and will require you adding a computer / wiring to the trans. It has been done many times as well.

I'll touch on t-cases, there aren't too many choices.

D-20 - I think your 71 is the T-shift pattern. If so, it has a slightly lower gear than the later J-pattern D-20s (2.38:1 j vs 2.46:1 t). If you have a J pattern D20, the 2.46 gear can be installed during a rebuild. They are good t-cases, and you can buy upgraded rear output shafts, they seem to be the one weak point. I've twin sticked mine and would recommend it. Its a little harder to twin stick a T-pattern case than a J-pattern case, but there are lots of guys who can help with either. If you change to an AOD, EAOD, or the 4R70W transmissions, you will need to buy an adapter. You didn't say what trans you have now, I'm curious. You can get 2 aftermarket low gear sets, lower than either stock option, but then you are getting pretty expensive.

If you change to a more modern OD trans (AOD, EAOD, 4R70W) there are some t-cases that will bolt right up to those transmissions. I think the NP205 came in lots of 4x4 trucks in the 90's, and they bolt right to the trannys from the 90's. This tcase is bullet proof, but it is only a 2:1 low ratio, and either stock D-20 has a lower low gear than the 205. There might be fittement issues, but its been done, you could probably find info on Classicbroncos.com

If you want to go big, and get a modern OD trans, then an Atlas t-case will bolt right up, with other major fabrication & modification. They are expensive $2000+++, but bomber, and can be had in many gear ratios up to 5.0:1. There are also 4 speed versions that will gear you down to 11.7:1.

Lots of great points. I'll throw my $0.02 in seeing as I am still awake...stupid late evening coffee.

Best and easiest are hardly synonymous. Especially when we consider your goals for the build. But maybe they are. Assuming that at the moment you have a 302, 3 speed transmission, and a T shift Dana 20 transfer case, let's build on that.

Slapping an Explorer EFI system, or most of it, with the serpentine belt system would make for a very nice, and easy, upgrade to the current motor. And it should be fairly economical. As stated before, picking up a decent used 5.0 from the 96-99(ish) Explorer has its benefits too. It would be a roller block. It would have GT40 or GT40P heads on it. And the total cost to pick up the entire thing, versus picking up the EFI parts, serpentine parts, etc. could be cheaper than sourcing everything from a pick and pull type salvage yard. Plan to to a rebuild on it just for safety though. Everything should fit under the hood with little to no clearance issues, considering it is the same motor, just a later version. Some variations do exist where guys have had to do a small body lift or put on an aftermarket fiberglass hood to clear things.

From the transmission perspective, modern is nice. However, the C4 automatic, which was stock in Broncos from 1973-1977 (read: direct fit, very easy to swap out) was, if I recall correctly, the longest production automatic transmission Ford made. 1964-1982 (1986 if you factor in the C5 variant). C4s are used by drag racers, hot rodders, and people doing V8 conversions in to Rangers and the like still today. It's not flashy. It's not overdrive. But it gets the job done and doesn't take much to put in. And with some modifications, it can easily handle anything you are going to throw at it on the trail. (If you'd like to know more about those modifications and what all is entailed, pop on over to AplineClassicBroncos.com and talk to a member over there named Viperwolf. He's built many C4s for guys here and over there and anyone who is running them will tell you it is worth the money.)

Now, I don't know what your daily commute is like, but if you are like me you really don't care about how far it is and how fast you get there. When I'm in the Bronco driving to work, it's all about the drive. But then I have the luxury of having another daily driver for those days when I do want to push the skinny pedal hard. If fuel economy and long highway drives may be in your future, then I would certainly look towards an auto with an overdrive option.

On the transfer case, you are simply not going to go wrong with sticking with a Dana 20. It's classic. It's tough. And you already have one. The NP205 is about 80 pounds heavier than the Dana 20, has a higher gear ratio which cannot be lowered economically without the creation of a "doubler" (add about 6" to the length of your drivetrain), and would require you to fabricate a cross member to hold it. Plus, depending on which transmission you opt for, could put a lot of unneeded stress on your transmission. As Gunni said, adding a twin stick kit is a good way to add some options when it comes to off road use. The T shift can be twin sticked without the PITA modifications, however it negates the ability to run your truck in front wheel drive only mode.

So, personally I would say your best and easiest path here is a 5.0 Explorer motor tied to a C4 and your Dana 20. If you wanted to kick it up a notch, you go with a 5.8, 4R70W, and D20. And if you want to go hog wild, rip that Dana 20 out and drop an Atlas in there. But I don't think you will be doing anything with this truck that will warrant that type of hardware. A bit like prairie dog hunting with a 50 caliber Barrett.

Thank you all for your input. I am sure I will be asking more questions as we get started on the project.

Great recommendations guys.

Just one note, a T-shift does have a hard to find 2-low option. And a mild wheeler isn't interested in front digs, so a twin stick in a T-shift may not be necessary. Back when my rig had a T-shift, I used the 2-low fairly often for loading on a trailer, or maybe dragging something else onto a trailer etc, not to mention turning sharper on the trail if I could disconnect the front axle. But it was not easy to find that sweet spot, but it is there. Take a look at any T-shift replacement knob and you'll see 2H right next to Neutral.