ive had my tranny re built, its fine but 1st gear judders reall bad almost like its not gonna move, once its in second its perfect, if i put the car in overdrive it does not have the problem but does drive as well as it should.
Could it be the band slipping? as the car does not move untill you ease off the power

 

the rebuilder must have messed up somewhere. Maybe forgot to install the correct number of clutches in the forward clutch pack or in the low reverse clutch pack. or installed the wrong thickness ones, or possibly tore the rubber or sealing rings during fixing it. Sounds like it will have to come back out. DOH

 

i hope it does not need to come out, the guy that built it knows his stuff, its alright if u pull away gently and fine in over drive which i cant understand, surely it should judder in overdrive as well