I've searched the web but cannot find much information on the subject.

What rear axle came stock on a 47 half ton?

What gearing?

I'm swapoing a 351w and a c6 into the truck. Should I probably swap the rear end out as well?

If so, Is there a market for a used original one in good shape?

 

A mid 90's explorer rear end works really good. The only drawback is it has a different lug pattern.

 

Yeah that's the plan most likely. I don't mind going 5x4.5 because I'll be redoing the front at the same time so I'll change those to whatever bolt pattern the rearend has.

I'm really just curious about the old rear end. Is like to know what it's geared to and if it might be something I can sell.

 

Most likely it is 3.78 or 4.11. It will be stamped on the center member with two numbers, like a 9 and 37, they will tell you the number of teeth on the pinion and ring gear. Sometimes they are stamped fairly light, you will have to use a wire brush to find them.
Mark

 

A 9 inch axle from a 57 to 72 F-100 is darn near a bolt in deal. The stock axle shafts are a bit small for a strong 351W.

 

When you did the rear end swap, did you have to get a custom drive shaft made or were you able to use your stock driveshaft? If you had to get one made, where did you get it made?

It seems like I would have to get a custom one since I am using a C6 transmission.

 

I haven't personally made the swap. I have crawled under a a friend's 47 pickup and one of the 66 F -100s I owned and measured everything up. From my memory you will need the following:
1. The u-bolt plates from the 9 inch since it is larger diameter than the stock axle. Even better is the spring plates from an F-2 since they also include lower shock mounts. PM me for more information on these (my brother has a pair).
2. New u-bolts. New high quality ones are cheap enough it is not worth using junkyard parts unless you already have a set.
3. You have to figure out the flex line for the rear brakes. I think the stock one will work, but maybe not.
4. I think the hand brake cable will work with the F-100 brakes, but I didn't take these apart to verify.
5. You will have to change your drive shaft. I have no idea how different this will be for you since you are also changing the transmission.

 

Will I need pretty much the same thing for an 8.8 swap?

Those are a lot easier/cheaper to find.

I will keep looking for a 9 inch. If I find one I will get with you about the U bolt plates. Unless you think they would work for the 8.8 as well.

 

Depending on what you are changing on your truck you will probably be money ahead going with a 9 inch. I am not aware of an 8.8 inch that will install without other major (expensive) things done. Things to be aware of on a rear axle swap:

1 - spring hanger width. If the distance between the spring hangers is different than your original axle then you have to modify the suspension on your truck or move the hangers on your replacement axle. Either costs time and money.
2 - total axle width. If your replacement axle is too narrow or too wide you get to mess with wheel back spacing and / or wheel spacers. Buying custom wheels to go with your bargain axle is probably going to be expensive.
3 - wheel bolt pattern. The early F-100 9 inch already has the bolt pattern to match the front of your truck. The 8.8 inch probably doesn't.
4 - axle ratios. Finding a rear axle with the exact ratio you want may be fairly easy. If not, you get to change the ring and pinion. 9 inch axles are about the cheapest ratio change in the history of rear axles.

I'm not saying that an 8.8 inch is a bad idea for a hot rod. Think about all the other changes you plan to make to the truck. If the changes required to install an 8.8 are already in the budget (both time and money) then it probably make sense. If not, you are probably robbing Peter to pay Paul.

 

I was under the impression that the late 90's explorer 8.8 is the correct width. I may need to move mounts, but I can do that with out much problem.

The problem I am running in to is that the f100 9 in. are very expensive. I can get the 8.8 much cheaper.

Changing lug pattern isn't a problem because I am upgrading the front brakes anyways.

I'll keep looking for an f100 9 inch. I am not in any big hurry.

I do have access to a 1982 f150 9 inch, but its too wide.

 

From what I remember, the 8.8 was really close in width. Maybe 1/2" too wide or narrow. I went to Orcheln's, and picked up a set of spring hangers for $7.00, and welded in. It was really easy.

 

You can get an 8.8 for a fraction of the cost of a 9 inch and they are plenty strong enough for a daily driver, plus lots of them have a limited slip already. Your stock rear end should be a banjo type and the 42-47 are open driveline so they have some desirability. This is the only banjo rear end that wasn't an enclosed drive.