I am fixkn to make an offer on a truck. 79 f150 4x4 but has 3/4 ton axles. It is missing the front driveshaft. The owner says it was missing when they bought it. He claims that rhe transfercase yoke turns when 4x4 is engaged. What should ibe concerned about? Front differencial? How can i know everything works? Are all frontdriveshafts interchangeable? How hardwill it be to find a replacement driveshaft? Thanks guys.

 

My uncle says on deals like that, just figure nothing works, make your offer based on that.

 

You should be able to get a driveshaft out of either a 1/2 ton or a 3/4 ton at a junkyard but you will need to measure the shaft and make sure it will fit. Either way there is a very good possibility you will need to take the new shaft to a shop and have it modified to fit.

To check and see if things are good in the transfer case you could lay under the truck while some one slowly drives it back and forth to visually verify that the output shaft is turning. I would also test drive it with the transfer in both 4 hi and 4 lo to make sure that there are no strange vibrations or noise coming for it. For the axle I would lock the hubs in, jack up the front end and spin the input shaft by hand to make sure that the shafts are all turning. You could also test drive it with the hubs locked in to make sure there are not strange noises or vibrations coming from it with the hubs locked.

In my experience there is typically a reason someone didn't finish their projects. If it were me I would use it as a good negotiating point and try and talk him down $500 for, depending on the condition of the rest of the truck. I would also wonder why the P.O. put 3/4 ton axles on a 1/2 ton. Were they converting to a rock crawler or trying to use a 1/2 ton as a 3/4 ton for towing and hauling? If it's the second scenario than you have to assume that the truck has been used and abused and that other drivetrain, suspension and powertrain problems/wear and tear exist.

 

Tocheck the front axle, can u jack it up and lock in the hubs to see if the hubs and differencial work?

 

yes, read above post

 

lets ask the big question here. is the front suspension coil springs or leaf springs? if it is coil springs a good guess would be they switch the outers on the front axle and put a eight lug axle of some kind in the back and the front gears dont match the rear gears.

 

Here it is.
http://tallahassee.craigslist.org/for/4293404015.html

 

Lookslike coils in the front.

 

looks like it has had a repaint some time in its life. crawl around underneath the truck and give it a good look. not a bad price but i bet there is some wiggle room.

 

The issue is that it is 4hrs from me. What about the gearing u was talkkng about?

 

the front and rear axles have to be geared the same. if the fronts dont match the rears the truck will not drive correctly. i am not really familar with what truck came with what gears but lets say the rear has a 4.10 gear ratio. then the front should have something similar like a 4.09. someone with more knowlege about it will be along im sure.

 

There are two ways to check the gearing. The first way is to check the axle tags, most trucks in this era are probably missing that though. The other way is to jack up the axle in question, take some chalk and mark the tire and the drive line and slowlt turn the tire one rotation while counting the rotations of the drive line. If you have 4.10's the driveline will rotate 4 times to one rotation of the tire. If you have 3.55's the drive line will rotate 3.5 times per 1 rotation of the tire.

 

How would u recommend doing the front since it has no driveshaft?

 

Also, is it justthe front and rear axle that needs the same gear ratio,or is the transfer case suppose to have same ratioas the axles too.

 

If you mark the output shaft on the axle it would rotate the same number of times as the driveline.