Fuel economy for 89' IDI. (Transmission)

[TorchMadness]

What year is the ZF? I think 1992 and up didn't use a speedo cable rather a sensor on the rear axle. Your 89 truck has a cable. Possibly the ZF (if newer than 91) can be adapted for the cable??? Someone on here will likely know........

Don't know exact year but it has spedo port