Digging through the factory bin that I have loaded right now in TunerPro on an 8051 ECM for my LT1. The motor/EFI is currently installed in a '62 IH Scout, with an old school SM465 4 speed manual, and a NP205 transfer case. The case is currently set up for a mechanical speedometer, which obviously doesn't work with the EFI.

I noticed there is a "Speed Pulses Per Driveshaft Revolution" scalar in TunerPro, currently set to 40. Which makes sense, as the stock sensor in the original application would have used the 40 pulse per revolution VSS (computer is from a '94 Caprice 9C1).

I see Dakota Digital has a 40 pulse speedo drive adapter with factory style socket for $120, and a much cheaper 8 pulse adapter for about $30. Since I don't need the factory socket, can I use the cheaper one and just change the Speed Pulses value in TunerPro to 8?

I also noticed the 40 pulse adapter is a 3 terminal plug, whereas the 8 pulse is a 2 terminal. Is there another reason I would need that 3rd terminal?