Better mileage than average new passenger vehicle in 2.5ton commercial truck!

[Christ]

If you can get the complete rear end, it's just a matter of disconnecting the brake lines and unhooking the shocks and springs, driveshaft, then swapping them out. It's a couple hours work once you get used to it.

Once the new axle is on, bleed your brakes.

A complete rear end swap is much faster than a gear swap.

[JacobAziza]

When you say "complete", you mean even the wheels?

[Christ]

Well, no... But it wouldn't hurt to have a spare set, if you can get them with it.

Basically, I mean the complete "stick". The gear housing (pumpkin), the axles, the axle tubes, and hubs, including the brakes and drums.

You don't need the leaf springs or shocks, and you should have the brake lines from each side to the junction point near the middle of the "stick". Basically, everything between the wheels, but nothing else is needed.

[JacobAziza]

Right, I meant hubs.
I'm thinking in bicycle terms (where "wheel" includes hub, and the part the tire is mounted on is a "rim")

So, replacing the entire axle would be easier than separating the differential from the center or replacing the gears inside the differential? (Do they even come out?)

[Christ]

The gears do come out, and the axle tubes on your truck are press-fit into the gear housing.

The easiest and fastest solution is to replace the stick as a whole unit. Changing the gear set requires more work and downtime, since you have to both gauge preload on the bearings, and the actual contact surface between the gears, to make sure they're not engaged too far or too little on each other.

Changing the gears inside the axle pretty much is a weekend project, where changing the stick can be done in a couple hours, even if you don't know what you're really doing the first time.

If you're going to get one from a junk yard, keep a good step by step record of what you did to get it off, then do exactly that to put it back on.

Basically, you'll put the rear end on stands, with the axle just off the suspension, and just off the ground.

You'll remove both shock cartridges.

Remove the single brake line from the middle part of the axle, but leave the splitter and the lines from it to each side.

Remove the driveshaft from the axle, not from the transmission.

Remove the hangers from the leaf springs, while supporting the axle with a jack under the gear housing.

Reverse to install, don't forget to bleed your brakes when you're done.

When you remove that brake line, cap it off, so you don't lose all your fluid.

[JacobAziza]

Sure doesn't sound like a couple hours to me...

But, yeah, I'll probably end up doing this.
After I pay off what I spent on the truck already recently...

Thanks for all the information!

[Christ]

You'll need PB blaster and air tools.

There are 4 bolts holding the leaf springs to the axles, 2 bolts holding the shocks to the axles, and 4 or 8 bolts holding the driveshaft to the axle. The brake line should be 7/16, I think...

When you park the truck the night before, spray all the bolts and the brake line with PB blaster. When you get up in the morning, while you're preparing to do the work, spray them again.

The only downside to swapping the whole axle is that you should have an alignment done afterward. There are nipples on the axle or springs that will fit into holes on the other, so you can't horribly misalign it, but you won't get it exact, either.

Honestly, once you see the work in front of you, you'll see exactly how easily it can be done.

[rmay635703]

GM is probably different than ford but the garage that replaced my rearend only took a little over an hour, parts were $35 labor was $100 If you have all the tools and maybe a friend it shouldn't take real long, I would guess much easier if you can lift your hole rearend up.

I ended up with 2.8's because that was what was available from his junkpile cheap, great mileage, similar power oddly enough (but I have an auto). These old non-turbo diesels have most of their power near idle so you should be OK.

You will need to figure out what your rear diff is and attempt to move up to a diff with high enough gears to make your 3rd similar to an OD gearing. You may find you can still pull from 2nd and 1st is still enough to pull the hills 20-25% higher gearing change isn't much to the low end gears but really shows on the top gears.

You could do more than that to make your gears into real highway gears but then getting 1st gear right (you would need to know its reduction) would be critical so you could take off without riding the clutch much.

So I guess it depends on how extreme you want to go, my 2.8's were overkill but something more reasonable 3.02's might work OK still.

What is your rearend reduction ratio now? 4.11's?

Cheers
Ryan

[elhigh]

I've done the rearend swap before, and he's right: it's a snap. I was only 17 and had access to hand tools only. Put the back end up on stands and get wrenching. It took me half a six-pack of Cokes and most of a sunny Saturday afternoon, but considering it was my first time working on the car myself, I think it went pretty smoothly. Careful eyeballing and tape measure work got the alignment really, really close to right on.

Get online and figure out if there's a VIN code that translates to a certain original axle ratio, and you can start crawling the junkyards looking for the speed you want.

[JacobAziza]

It has a 3.73 currently

From what I see online the only choices to go smaller are 3.06 or 2.73
After the hill I climbed yesterday (in 1 the whole way) I'm thinking 2.73 may be too big a jump, so I guess I know what I'm looking for.

Thanks