If you have an older model Compatible GM transmission and are using the programmable speedo set, dont forget your pulse generator. See the additional information below to see if this is needed for your application.+ Allows modern Compatible with GM engines to be mated to non-electronically controlled GM automatic transmissions.+ Converts mechanical speed signal into a digital square wave signal, at 128K pulses per mile, for you modern GM "engine computer"/speedometer+ 8000 pulses per mileTransmission types and required Pulse Generator: :C-4C-6 Tremec 5 SpeedAOD:All these require 4ed Pulse except some C-6 (Have screw on cables) therefore GM Pulse would applyGM:Turbo 350Turbo 400 (All require GM Pulse)200R4Power Glide700R4 Early Model (Require GM Pulse)--------------700 R4 Late Model (Already built in)4L60E (Already built in)4L80E (Already built in):GM: They will use their existing Speedo Cable as well to screw onto this mechanical Transmission - NAPAS Part #s 904 & 727 - Long Cable 615-1666 Short Cable 615-1665