I have a 87 F-250 dually with a 7.5l engine. It had a 3 speed auto in it but burnt out. I decided to switch it with a ZF5-S42 from a 94 F-450. Well long story short after many other alterations I am stumped on how to hook a speedo up. I didn't think that part through and I'm stuck without one. Do they make one that is interchangeable for my combo or is there anyway to rig one up? It is very aggravating not having one and relying on a tach. Any help is great and thank you.

 

it can be done but probably not at a mechanic's level...engineer or someone very good in electronics.
the electronic system speed sensor in the trans, sends an analog speed signal to a module. the signal s buffered and converted to a digital signal and the digital signal is sent to an electronic instrument cluster.

 

Could probably go the GPS interface speedo, or, just a GPS speed app on a phone would at least get you by.

 

Thats what I was afraid of. Sounds like BIG bucks. I knew there would be a few issues, I was hoping the drive shaft would've been the biggest but this speedo is. not only does the speedo not work but the odometer doesn't either. I love the 5 speed. Went from around 8mpg to almost 12. Not to mention driving 70 at 2,000 rpm is nice as well.

 

After some searching I found a company called "Bobs speedometer" that does these kinds of things. I will let you know if they can do it. Could be my answer.

 

After talking to a transmission shop I was told that in 92 Ford did away with the transmission mounted speedo and switched them to the differential. So I have 2 choices. 1 I can swap the Trans out for a 91 or older (which most likely won't happen) or I can swap out differentials with a 92 or newer (which is most likely what I will do). So now anyone else that comes across this problem will know the solution. Thanks everyone for the help!

 

are you saying the 92 differential runs a speedo cable or just a speed sensor? If its a speed sensor your no further ahead. I would be surprized to see a diff running a speedo cable.

 

I believe he is speaking of replacing the WHOLE differential, banjo housing and all I hope! I could be wrong there too!

 

I will have to change to an electric speedo cluster as well. I'd rather bust some knuckles and get dirty to keep from running a gps speedo. Plus it will make my odometer work. Bobs said he can change my cluster to electronic. I'd have to go that route because I'm no electronic major. I hate that stuff.

 

Sounds like Bob's knows what they are doing. Your partway to having a three channel antilock brake system lol.