transmission seems to slip only when in 3rd or 4th gear when driving i get to about 35-40 mph right when it shift into 4th the trans slips and it just free revs then my speedometer starts bouncing back and forth between zero and whatever speed im going anyone got any answers to this problem?

 

if you are free rev'n are you hitting your rev. limiter? my 1st trans did that when it was on its way out. is your oil burnt or dark brown?

if your speedo is going crazy check the sensor on the tail shaft of the trans mission. it is magnetic or something and reads off of the spinning gear in the tail shaft.