from post 139 " but the speedometer is a different story. The 4L60e uses an electric speedo when these old trucks use a mechanical one. It's ok I'll just use my gps for speed when traveling"
Dakota digital makes a elec to cable conversion box so you can keep your stock speedo....I used one in my 81 and it works great...a little spendy but im happy....
http://www.dakotadigital.com/index.c...rod/prd886.htm