losing power to the wheels

[thesmokin12v]

i have a 96 cummins 4x4 with a built 47 re trans and here recently the speedo quits working intermitenly the problem is when it stops working it loses all power to the wheels its like it free revs then as soon as speedo starts working its fine im losing my mind over this problem any help would be appreciated thanks

 

[mathews8pt]

have you tried a speed sensor?

 

[thesmokin12v]

no but i didnt think that the speed sensor would cause it to lose power to the wheels but that a cheap place to start it seems to me that it did it after i put a ts lock up controller on it