magnetic speedometer adapter

88 cherokee, ax-15, adapting to a 241 rocktrac.
looking for a way to adapt the mechanical speedometer to a magnetic
pickup. remember reading something about a dakota magnetic pickup.
any references to that thread or an aftermarket solution would be helpful.
TIA

The "Dakota" converter is for the electronic speedometers for calibration of different tires/gears.I have not seen an electronic to mechanical converter.