Axle width

[70CHEVYBB]

Does anyone know how wide a 70 axle is. that would be axle flange to axle flange. Will a late 70's axle fit if I change the mounting pads. I have 2wd truck and need a posi

[CC69Rat]

Yes sir ..

Early rear end housings are 1.5" more narrow than the later rear housings. An easy way to tell (especially if the rear end is still in the truck) -- Thanks Keith -- If you measure from the back side of one brake mounting plate to the other the early housing will be 55.5" long. The later one will be 57". The axles are 30.5" from the flange where the wheel bolts on to the end of the splines. (early) and 31 5/16 on the later models. What I am saying here is if you have the early housing, you wouldn't want to just swap in later model 5 lug axles they'd be too long. I have never seen a set of 5 lug in 30.5" long OE axles but I have been told they exist (?? Can't see how) But .. just saying.

If youre junk yard hopping and find some they're probably 70+. I had a 70 with the later rear end housing in it but as I understand it in 70 they could have either. 55.5" housings are usually 6 luggers. .. but they are more disarable to build because you can run .75" more offset (less backspacing) and it makes your wheels look a little wider. You have more of the fat lip look to the outside.

Likewise, be careful using measurements from other trucks you may see and/or hear backspacing measurements .. Ex. 5.5" BS on my wheels but interchange from housing to housing they'd fit completely different.

Hope this helps man. Backing plate to backing plate is the easiest way I know to measure them. later ..

[fp1967]

Yes, a late 70's axle will work if you change the mounting pads. They are the same width as the 71-72's and the wider 70's. Actually all of the 1970's that I have seen were the wider ones, it wasn't until I started reading on this site that I learned some of the 1970's had the narrower axles.

[BrianG]

Question.... Does this apply to both the 2wd and 4wd? Meaning were the back narrower up through 70 for the 4wheel drive also?

[fp1967]

Yes, 4wd also. Narrower up through 69 is what I've seen. I've had a couple of 70 4wd parts trucks and they had the wider rear axles in them.