I got a 9" rearend out of a 1969-70 F100 to go in my basically stock 1954 F100. My understanding was it was a straightforward bolt on swap for the stock one I took out of it. Is that in fact the case? Anybody that can share a pic of how it attaches to the springs would be most appreciated. It's been a while since I took the other one out and I do not see it covered in my shop manual.

Any other tips/watchouts as I tackle this are welcome.

 

It is, in fact, the case. It is a direct bolt on operation. Jack up the truck, take the old rear out, put the new rear right back in it's place. The springs will sit right down on the pads on the housing just like it did on the old rear.

 

If the rear axle is like the one in the earlier '48-52 trucks you'll have to make shock mounts. I haven't done it yet but I've read all of the posts on how to do it. I have a page on my web site describing how MTflat did it in his Bonus Built truck:

Rear Axle Page

 

drive shaft length UBolt diameter, and UJoint size may be of concern.

 

I also have a 54 and my rear end came out of a 71 F100. Bolted right in. The rear brakes are wider so make sure to get the drums, your 54 drums won't fit. I did use stock parking brake cables, too.

 

bolted right up in my 56. shock towers and all. use the brake cables, as stated. watch pinion angle, you may have to use some shims to make it right. you need 30*

 

I think (hope!) you meant 3 deg., but 6 deg. is the angle of a Bonus Built engine/tranny, don't know about mid-fifties, 30 would be for a monster truck!

I kind of hate to see this swap described as a "bolt-in", it really isn't (maybe on mid-fifties?). It's as close as you'll get, for sure. As Fergusonic points out, there's more to it. Figure $100 minimum for driveshaft mods and balancing alone, new spring plates are needed, the shock mounts can be a significant effort or cost, and you likely aren't going to slap on the "new" diff with old boneyard brakes, old axle seals, and old bearings (MT Flat got really lucky!). After all that you find out if the "new" unit was a noisy POS and needs a rebuild. I honestly wonder if it's really cheaper than having the stock diff rebuilt with new gears? I was quoted ~ $750 for a very thorough rebuild with new gears, new carrier, and all new diff bearings. It would be done in two days, too. Hmmmmm.....

 

the only cool thing about a 9in is the ability to swap the whole gearset in one exchange.. without removing the whole rear assembly..

Sam

 

Yes, definitely some things to think about. I got the rear springs installed today (had them rearched) and the rearend is ready to attach. I measured and it looks like it will bolt up okay. The rearend I found included the drums and the emergency brake cables are intact. I think it is in good shape but I wont know with certainty for a little while.

From a diagram I saw it looks like I need a bracket that the ubolt bolts to that fits underneath the axle after it is aligned with the spring. I did not see a part number for it but I can't see how I can attach without it since the newer axle is a bigger diameter than the old one and I cannot use it.

 

oops. ment 3*, and zapped a 0 on the end. sorry. use the plates and ubolts off the donor truck, and yes, do replace axel seal, and brake parts.

 

That's where the stock shocks would attach, too. That's one of the "little things" that isn't the same. You can use an F-2/F-3 spring plate but they are getting hard to find (they had 3"-dia axle tubes too). Several vendors sell aftermarket plates that will do it, or you can make your own. MT Flat relocated the brackets that came on the new axle. They need to be pretty stout and stiff plates, look at the vendor stuff. The U-bolts need to clamp down tight.

Most of the donor axles I've seen didn't use the bottom plate as the shock anchor.

 

fat man fabracations sells a kit.

 

I guess I used the wrong term. It's actually a plate that fits under the center of the spring and the u bolt comes down from the topside and is fastened together with a nut. Forgive my poor terminology. Clear as mud. Right?