I found a truck I want to buy but it has an issue that may cost more than I think.

The truck is a factory tubo 7.3 IDI ZF5, for some reason the rear Dana 80 was swapped for an earlier version that has no provision for the VSS on the housing. The spedo and ODO don't work, the seller says he bought it from his company and they put a new (from ford) engine and reman trans in it serviced the rear end but neglected to re fill the oil so it seized up. He sounds very knowledgable about IDI diesels and the truck looks like a good deal but am afraid I will have to swap rear ends, time and cash consuming.

So can I put the VSS in the ZF-5? Is there an unused port on it? It has the E brake mounted on the back of the trans.

 

There probably is a way to put it in the trans but it's going to be off by the rear end gear ratio. If the ratio is 4.11:1 the transmission output shaft is spinning about 1/4 the speed that the VSS would be expecting. At an actual 80 MPH your speedo would read just under 20 MPH.

 

I did not even consider that. All my searching and reading says that some IDI trucks had the VSS in the tail housing of the ZF and some were on the axle housing. I think the correct fix is a new rear housing with the VSS port. The bummer is the Dana 80 in the F-superduty is really only good for that truck making it less desireable but the "It's a Dana 80!!!" factor really up's the price.

 

`91 and earlier the speedo was cable driven. There would have been a port on the transmission adapter housing (between trans and brake assy.) with a drive gear on the trans output shaft. `92 up the speedo was electronic, driven by the sensor on the rear diff housing.

 

So what year rear axle will work? 92 up to 97? Are all VSS mounting points the same? This is a Dana 80 for an F-Superduty (F450)

 

Spoke too soon, found one out of a 97 for $200. Any issues with putting a 97 into a 94? Vss the same? Brakes?

 

On the lighter duty trucks there was a rear anti-lock brake system fitted from `87 up which used a speed sensor in the rear axle, I don`t know if the F450 used that as well from `87. If they did then an axle from `87 would have the fitting.
I would think that the `97 axle with VSS would do however I don`t know if they changed the brakes.