Does any one know the length of the speedometer cable for a 78 hilux truck with a manual trans? The owners manual says how to disconnect and connect but not the actual length. The parts stores are selling 2 sizes 75" and 90"

 

The info I have on this is strange. My sources say the 75" cable was used up until August 1978, then the 90" cable was used from August to October 1978. The 90" cable was also used on 1979 models, which was the first year for that particular re-design of the truck. From 1980 on they show a 75" cable.

Given this weirdness, probably the best thing to do is remove your old one and measure it (sure thing), or maybe check your vehicle ID plate to see what the date of manufacture was. The plate on a '78 should be located on top of the driver's side wheel well, under the hood, near your Igniter & Ignition Coil.

 

@13Swords My truck is made in June. Thank you for the info and doing the research where did you find the info? The Haynes book I have does not have that info.

 

It was a matter of checking out what was available for speedo cables on Rock Auto. I've learned it pays to take a look at the previous and next year models to see if there are any differences. Often, the parts listings themselves will have extra info tagged on them, like the different lengths/dates used etc.

My best guess on what happened in your case is that for the newly designed model in 1979, Toyota (for some reason) wanted to go to a 90" speedo cable. As they were finishing up the late-year '78s on the line, they may have run out of the 75" cables, so just used the 90" cables instead. Given that the parts listing only shows them being used for 2 months, my guess is that they didn't order enough 75 inchers to complete the model year run. But since the trucks needed to be completed and shipped out, they used what they had on hand. I also think that they started using the 90 incher for the '79s as planned, then realized that they were actually too long, so they switched back to the 75 inchers in '80. You can see this if you check the parts listings on Rock Auto for that part on all three years.

There are lots of small (or not so small!) parts differences on these pickups, where Toyota got some brilliant idea for a change, then reverted to the original design later. Example - the '79 models had the 20R engine, with the original electric fuel pump in the tank system. But '80 to '83 models had a mechanical fuel pump mounted to the head, even with the introduction of the 22R in '81. In '84, they went back to the electric fuel pump in the tank system, for both carbureted and electronic fuel injection models, but there are differences in the electric pumps between carb & EFI (different PSI ratings).

So basically, just carefully reviewing the parts listings for different years can tell you a lot about design & engineering changes in the trucks and when they happened. Why they happened is admittedly guesswork on my part, but I think my guesses are reasonable.

The Haynes manual is good to have in hand but isn't exactly complete; only the original Toyota Factory Service Manuals are, and even those are subject to update service bulletins (concerning changes, recalls, etc.) that came out at the time, but are never included in the manual.
If it's any help, here's a link to the Muir "How To Keep Your Toyota Pickup Alive" manual online in PDF form. I have this downloaded to my computer as well for reference.
https://toyotachinook.files.wordpres...ckup-alive.pdf

Let me know if I can help with anything else. I've pretty much been through every system in my '78.

 

Not quite.

Toyota stayed with the mechanical fuel pumps on 22R carbureted trucks all the way up until they discontinued the 22R. The 22R-E has an electric in-tank fuel pump.