i found a 4L80e bout 20min away and the guy says hes askin $475 for it, but will take $400. it was rebuilt 1.5 years ago so it should be in good condition. my question is, how do i bolt a doubler up to this? i know the 4l80e is electric speedo, and my truck is mechanical, but what is the best way to go about this? im debating bout getting the computer since i could get the tranny so cheap. what are my options?