My trucks not stock? Gearing concerns...

[86-350-460-dually]

I bought this truck, thinking it was stock. We've since discovered the coil is not stock, the rear end is probably not stock and it might not have been a dually or 4wd at conception.

I just keep finding new things about it. I was hoping maybe someone could help me identify the make and/or model of the rear axle and if it was stock on this truck.

I'm a little concerned because my speedometer is way off. It starts at zero, but by the time I hit 60 mph, the spedometer is at 82 mph. Should I be concerned about the gearing on the truck?

Anywho, I suppose first things first.... Is that the stock rear axle?

[Rembrant]

I just keep finding new things about it. I was hoping maybe someone could help me identify the make and/or model of the rear axle and if it was stock on this truck.

That's the onion Gary is always talking about...lol. Each of those new things you find out are a different layer of the onion.

Luckily we have experts on here that can tell you exactly what rear diff that is. I'm not one of those experts, but a quick comparison with the page below tells me that you have a Sterling 10.25" rear diff.

https://www.autoanything.com/drivetrain-differentials/how-to-identify-your-differential

We'll have to wait for Gary or Lebaron to drop by to confirm, but I do know that the F350 trucks had different rear ends depending on whether they had beds on them or not.

In the meantime, you should post a picture of the truck's certification label. It should be on the cab, just inside the driver's door by the striker post. That will identify what was in the truck when it was built.

[85lebaront2]

First item, if it was built as a cab and chassis, it should have the Dana 60 rear axle. Quick check without pulling everything apart is the track width. Cab and chassis trucks have a narrower track width than the dually pickups in 1985-86. The 10.25" Sterling rear was introduced in 1985 and the track width was increased, this allowed the between the fender width of the bed to be the same as a single rear wheel truck.

Drive through some water, continue straight and get out and look at the tire track pattern. A cab and chassis or pre 1985 dually pickup will produce what appears as a very wide single track on each side. A 1985 up dually pickup will produce a 4 tire track pattern.

The reason for this is the Dana rear, the center line of the dual wheels is in line with the center of the front wheels, on the Sterling, the center line of the inner dual is in line with the center of front wheel.

Axles ready for parts swapping, rear is an SRW Sterling, same width as a Dana.

[Gary Lewis]

First item, if it was built as a cab and chassis, it should have the Dana 60 rear axle. Quick check without pulling everything apart is the track width. Cab and chassis trucks have a narrower track width than the dually pickups in 1985-86. The 10.25" Sterling rear was introduced in 1985 and the track width was increased, this allowed the between the fender width of the bed to be the same as a single rear wheel truck.

Drive through some water, continue straight and get out and look at the tire track pattern. A cab and chassis or pre 1985 dually pickup will produce what appears as a very wide single track on each side. A 1985 up dually pickup will produce a 4 tire track pattern.

The reason for this is the Dana rear, the center line of the dual wheels is in line with the center of the front wheels, on the Sterling, the center line of the inner dual is in line with the center of front wheel.

Axles ready for parts swapping, rear is an SRW Sterling, same width as a Dana.

SRW width backing plate to backing plate.

DRW width backing plate to backing plate.

It looks like things are pretty well answered, but the rear axle info is here: Driveline/Axles & Differentials. On the Rear Axle tab you can see the illustration that shows where to find the tag or info on the axle. Note that the Dana info is on the axle tube.

And from the certification label you can get the axle code and look it up here: Specifications/Axle Ratios. Use rating info to figure out what it is via the Axles & Differentials page.

[Rembrant]

First item, if it was built as a cab and chassis, it should have the Dana 60 rear axle. Quick check without pulling everything apart is the track width.

Hey Lebaron,

Another quick check would be the cover bolts. If you look at the covers in the link I posted above, the Dana 60 cover has 10 bolts, and the Sterling 10.25 has 12 bolts. I have no idea if that is a 100% accurate chart, but if that chart is correct, then his rear diff appears to be a Sterling unit.

The certification label will give us an idea of whats going on here...on what the truck was supposed to be at least;).

 

[86-350-460-dually]

First item, if it was built as a cab and chassis, it should have the Dana 60 rear axle. Quick check without pulling everything apart is the track width.

Hey Lebaron,

Another quick check would be the cover bolts. If you look at the covers in the link I posted above, the Dana 60 cover has 10 bolts, and the Sterling 10.25 has 12 bolts. I have no idea if that is a 100% accurate chart, but if that chart is correct, then his rear diff appears to be a Sterling unit.

The certification label will give us an idea of whats going on here...on what the truck was supposed to be at least;).

Thanks everyone! I took a picture of the certification label and went to the ratio page on Gary's website and found that the 65 rear axle meant that it was supposed to have a "Dana/Spicer" rear axle. That's as far as I had gotten with it.

[85lebaront2]

First item, if it was built as a cab and chassis, it should have the Dana 60 rear axle. Quick check without pulling everything apart is the track width.

Hey Lebaron,

Another quick check would be the cover bolts. If you look at the covers in the link I posted above, the Dana 60 cover has 10 bolts, and the Sterling 10.25 has 12 bolts. I have no idea if that is a 100% accurate chart, but if that chart is correct, then his rear diff appears to be a Sterling unit.

The certification label will give us an idea of whats going on here...on what the truck was supposed to be at least;).

Correct by the information you shared. I did a cover bolt count and came up with that. He could have an SRW Sterling as the wheels would fit like they do on a Dana and would clear his springs also. I learned about the difference right after I bought Darth, the inspector showed me the difference in the width, the station had a 1986 F350 cab and chassis wrecker, built in Norfolk, wrecker body by Dynamic Industries, located across the street from the Ford plant. They had some sort of deal set up where I believe the trucks were ordered through a dealer (on paper) but delivered directly to them.

The wrecker rear duals would clear the base of the twin post lift in the inspection bay, Darth's would have run over the anchor bolts. I used to have to pull in from the back, but then back out to avoid running over the anchor bolts.

[86-350-460-dually]

Correct by the information you shared. I did a cover bolt count and came up with that. He could have an SRW Sterling as the wheels would fit like they do on a Dana and would clear his springs also. I learned about the difference right after I bought Darth, the inspector showed me the difference in the width, the station had a 1986 F350 cab and chassis wrecker, built in Norfolk, wrecker body by Dynamic Industries, located across the street from the Ford plant. They had some sort of deal set up where I believe the trucks were ordered through a dealer (on paper) but delivered directly to them.

The wrecker rear duals would clear the base of the twin post lift in the inspection bay, Darth's would have run over the anchor bolts. I used to have to pull in from the back, but then back out to avoid running over the anchor bolts.

So it's very probable that my truck originally only had 4 wheels and someone made it a dually?

Would you be concerned about the rear axle, if you were me? Is it stronger or weaker? Because my speedometer is off by 20+mph, are you concerned about the gear ratio?

[Rembrant]

So it's very probable that my truck originally only had 4 wheels and someone made it a dually?

Would you be concerned about the rear axle, if you were me? Is it stronger or weaker? Because my speedometer is off by 20+mph, are you concerned about the gear ratio?

According to your certification label, your truck was built/sold as an "Incomplete Vehicle" and was ordered by or shipped to the Denver CO area.

It is an F350 4x4 cab/chassis truck.

The "F38" is F350 4x4 regular cab cab/chassis truck.

Rear diff was originally a Dana with 4.56 gears.

Engine is 460, and trans is a T-18 4spd.

I don't see any way to identify if it had DRW or not...maybe Gary knows?

If it has a Sterling 10.25 in it now, perhaps it was changed.

I'd see if I could get a look at the data stamp on the rear diff and see if you can figure out what is in it for gears...that might explain the speedo difference.

 

[86-350-460-dually]

According to your certification label, your truck was built/sold as an "Incomplete Vehicle" and was ordered by or shipped to the Denver CO area.

It is an F350 4x4 cab/chassis truck.

The "F38" is F350 4x4 regular cab cab/chassis truck.

Rear diff was originally a Dana with 4.56 gears.

Engine is 460, and trans is a T-18 4spd.

I don't see any way to identify if it had DRW or not...maybe Gary knows?

If it has a Sterling 10.25 in it now, perhaps it was changed.

I'd see if I could get a look at the data stamp on the rear diff and see if you can figure out what is in it for gears...that might explain the speedo difference.

This is the only stamps I have found on that differential. These are all on the forward side of the differential. Very hard to read.