308 QV Pulse Generator Connections

Looks "homemade" to me. There might be some markings on them (under the grime). I would've guessed capacitors added to suppress noise, but one of those wires is a +12V DC power line (so maybe inductors or just direct connectors?). There is some evidence that the connectors to that pulse generator (and the pulse generator itself) have changed over time -- the SPC figure for Mondial 8 shows something more appropriate (a boot cover) for the female spade terminals on your harness wires (so those items were added just as a way to convert the connections from spade terminals for the early 113962 pulse generator to the round pins of the later 116987 pulse generator pigtail:

https://www.ferrariparts.co.uk/Diagram/Ferrari/Mondial-8/021-Gearbox-Differential-Housing-And-Oil-Sump

Is your 308QV a very early euro 308QV?

 

I have an 83 308 as well. I don't have those little boxes.

 

That odometer sender has nothing to do with the speedometer (mis)operation.

 

I sort of misspoke in my post -- I should've said that if your odometer is working correctly but your speedometer is not = can't be the sender or the wiring, and must be a fault in the speedometer electronics. If both the odometer and speedometer are misbehaving at the same time = justifies trying a new sender and/or checking the wiring (and your wiring does look a little dodgy and well-lubricated ).