Hey everyone, I'm new to the site and love it so far.
I'm sure this has been asked before, but I couldn't find anything on it. I'm getting ready to convert my '82 SC F150 from RWD to 4x4. I have done a couple of smaller builds before but never a conversion. Is there anything that I need to do special or different?
Also I already have the tranny, front drive shaft and transfer case. Thanks in advance and keep the dirty side down

 

This has been answered quite a few times. Just search 4x4 swap, 4wd swap, 4wd conversion etc. Hopefully most people in the future will find this helpful as well.

I've done this swap recently. It's a bolt in deal, (but a lot of them!) when using parts from a bronco or f150 from 80-96. I'll try to put together a list off the top of my head of what you'll need and a general run through of the job.

You need for up front:
1.Dana 44 TTB Front axle (make sure gear ratios match)
2.Brakes (rotors and calipers)

You need for the tranny/transfer case:
1.Either manual or auto 4x4 tranny.
For manuals:
4 speed with the bellhousing that matches (300,302,351w match)
5 speed that matches your engine since bellhousing cannot be changed. 5 speeds also have an integral slave.

Parts that differ from truck to truck:
1. Driveshafts, you'll probably have to get them cut or lengthened at a shop.
2. Crossmember for the transmission. Sometimes the old one works, flipping it over or turning it 180 may work, or you may need a new one.
3. Floorpan. The older 80-86, and the newer trucks have different locations for shifters I believe. The section of floor can be replaced for one with a hole, or do like I did and air hammer/saw/grind a hole and eventually get around to securing the boot onto it.
4. Speedo gears. I needed a new driven gear to get correct speedometer calibration.

A few things to remember:
1.Steering is the same. You should not need new tie rods etc, your existing steering setup will fit the new 4x4 axle.
2. If you have a speedometer cable, use an older year transfer case that accepts it. (I'm not sure how newer year speedometers are run).
3. If you want a lift kit, nows the time.
4. I believe 2wd springs, and shocks are reusable. (pretty sure at least)
5. 2wd rear leaf springs are 2.5 inches wide, 4wd are 3 inches wide. You don't need to change this, but it's nice to know.
6. Change the fluid before install (maybe by tipping it over with fill plug removed), or better yet fabricate a drain plug. I found out afterwards that my front diff must be siphoned out, or the diff separated from the axle to drain the fluid.


How to:
This can be done in two half jobs (transmission - front axle) if you don't have time for it all at once. Changing the transmission is pretty simple, just get a hand doing it if you can.

Removing the front axle:
1. Jack up the truck take off the wheels.
2. Disconnect your brake lines, sae the brake pads if you want to reuse them.
3. lower the truck so the rotors are just touching the ground.
4. Unbolt in order: shocks, coil spring clips, radius arms, the two bolt on the center crossmember.
5. You may have to lift the truck slightly to drop the axles, then slide out the radius arms.

Installing:
Before starting try to drain your fluid if needed, and change any bad u-joints.
1. Slide the two 4x4 axles together in the splines.
2. Connect the two axles together.
3. Slide it underneath the truck.
4. You may want two people, slide the radius arms up into place, start the nut on a few turns only to hold it.
5. Lower the truck low enough to attach the axle ends to the center crossmember.
6. Attach your coil springs and shocks.
7. Tighten everything down. Raise the truck up, everything should be on fine.
8. Setup your brakes, bleed them.
9. Anything left, tires, driveshaft etc.

 

Jason's got you pretty well covered so I won't rehash anything he said, except to let you know that newer trucks use a VSS (Vehicle Speed Sensor) in the rear axle to send a signal to the PSOM (Programmable Speedometer/Odometer Module) which runs an electronic speedo. No cable, no gears, nothing required from the transfer case (or trans if 2WD). So yes, you want a transfer case off an older truck (I'm not sure when Ford changed to the PSOM, but I'd guess around 1990 give or take a couple years).

You say you already have the transfer case, but for anyone still looking for one, the t.cases off newer pickups will have a slip yoke, requiring a different drive shaft. Most people (especially fourwheelers) prefer a fixed yoke (there are even slip yoke eliminator kits for some t.cases, but not ours). So you'd probably want one from a Bronco or an older pickup.

The good news is that apparently all of the Ford t.cases are interchangeable, at least as far as the transmission is concerned, so you don't have to worry about mixing and matching years (for instance, if you want a 5 speed overdrive out of a newer truck but want to stick with an older t.case for reasons already given). the exception to the interchangeable t.cases apparently is anything with a cast iron case. But you'll mostly find aluminum or magnesium cases in these years, so it shouldn't be a problem.


Edit to add: ad although it's important that the front and rear axle ratios match, you don't have to get a front axle that matches your current rear. If you want to change gear ratios this is the time to do it. Look for a front axle that already has what you want, then regear the rear to match it (or look for a matching rear axle too).

 

I have a dana 44 ttb front end and oodles of other parts if you are interested and near Caldwell, Texas or pay for shipping.