Looking to do an disc brake axle swap for a customer who owns a 1973 F250 Highboy. When I look at the junkyard for anything newer that 1976, they are asking if it's a full time or part time 4wd. I'm assuming the part time 4wd axle is the one I want, but just curious as to what the difference is in the axle. Also they separate out the crew cab front axles as well. What's the difference, or will any front axle from '76 and newer work, assuming it has the correct gear ratio?

Thanks.

 

Only difference I can think of is whether it has locking hubs or not originally.

Full time 4wd or AWD didn't have locking hubs.

Part time 4wd had locking hubs.

 

That’s all I can think of as well.
The high boy would have been part time, I’m pretty sure, because they all had locking hubs that I remember. I’ve seen some after 73 that had drive slugs, and no lock outs, but I thought they were still part time and the original purchaser just didn’t check the box for “free running hubs” at the time of the order.
But they could have received the 203 transfer case during that time frame. However, the overall fitment and design of the front axle would not have changed.
Other than perhaps the size of the yoke for the U joint, and the presence, or lack there of, of locking hubs.

And presumably you’re looking to replace the entire front axle assembly. Correct?
That’s because as far as I know, none of the later stuff will bolt straight to the high boy Dana 44.
So you’ll need the front axle assembly out of an F250 or F350 pickup truck between 77 and 79. Maybe 76, but I don’t know that transition era very well.
Or if you happen to stumble upon the semi unicorn F150 super cab Dana 44, it would have leaf spring perches as well.
But obviously all the wrong outer bits.

As far as the gear ratios go, they ran the full range from the 3.50’s to the 4.50’s during that time frame.
I think high boys were very commonly 4.10 ISH. Whatever the exact ratio of the 44 was at that point.
Not as common in later years, perhaps, but still out there.
Do you know the ratio in your customers truck currently? And do they want to change?

Sorry if you already knew all of that stuff. Just making sure you don’t stumble on the purchase and waste your time needlessly.

good luck!

Paul

 

Thanks for the replies. I can get my hands on a full hub to hub 8-lug front axle from a '76 F250 highboy.

One other question. Some yards list a 4.10 gear ratio, some list 4.09. Is the D44 a 4.09 and the D60 a 4.10, or are the yards just rounding up the 4.09 to 4.10?

 

don't worry about that... you can run them together. a dd44 with 4:09 has 45 ring teeth and 11 pinion teeth and 4:10 in the 60 have 41 ring teeth and 10 on the pinion. they are close enough that they won't cause any issues

 

A lot of crew cabs were 60's but they'll work.

4.10's were all that was available on high boys. maybe other ratio's were made in special circumstances but I've never seen one.

All the full-time axles I've seen were the small hub version 44. which is less desirable but works fine. hubs are easy and cheap for those.

 

Yeah, I guess I should have mentioned that part time 4wd didn't have to have locking hubs, it just seems they go well together. As to gears, I've read several places that my truck has 3.50:1 in the back 9", and 3.54:1 in the front D-44. ... but it just means that when I run in 4wd, the back pushes a little. Since part time 4wd was only intended for slick surface running where wheels spin anyway, it only takes a minor slip to get them back in step.

Might be I have the ratios reversed "F to R" ?

 

3.50 is a 9er ratio, 3.55 is a Dana. The 4.09/4.10 pairing is normal also.

With the different speeds the front vs. rear wheels turn in any corner and a slippery surface, it's not noticeable.

 

Hi boys were 410 gear to my best knowledge. A 1976 front axle should have compatible steering set up and be a low pinion so drive shaft is same if you go newer to a 1978-1979 axle then it is a hi pinion, might not work with current front drive shaft. I have seen a hiboy with full time 4x4 and drive lugs. And the ford owners manual lists it as an option as well. Parts and axles for these are becoming more rare around here every day, chevy folks are buying them up to build a real truck aout of a chevy so they are not easy to come by. Remember that generally when swapping from drum to disc, the master cylinder and proportioning valve usually do not interface. They likely will need to be swapped to compatible componentry.

 

Thanks for all the information. As for the master cylinder/power booster. That is missing from this truck. The owner swapped a 76 body on a 73 chassis. We are getting the boost/master/proportion valve parts from Master Power Brakes.

I called the junk yard yesterday to verify that they still had the axle, and they do. Surprisingly, they say it's still in the truck. Anything else I should ask for to help make the swap easier as far as steering components, to anything else. From what they told me it's complete from hub to hub.

 

Looks like everyone else has you lined out. As far as the JY axle, I'd get the complete truck. Nothing like a parts truck (trucks) on hand when working on projects.

 

If the customer will go for the expense buy a Benchworks power steering conversion. you'll both be so glad you did.