does your speedometer effect your computer/engine management?

[myfirstchevy]

since I am putting a TH350 in my car and it will be a cable speedo, will the factory electronic one effect the engine management? I talked with a guy at transmissionpartsusa.com and this is what he is telling me. I was trying to order the tail housing extension and he is telling me its the wrong part! so now I may just use the 9 inch tailshaft housing and move the torque arm to the crossmember.