3 speed ?'s

I have an a-230 3spd manual and I am looking to rebuild it. Does anyone know of any kits or buisness's. The 3rd gear is slipping pretty bad and allows no hard shifting for racing so I am forced to stick with 1st and 2nd. Which isn't too bad judging that i can take the car to 4000 and be at around 80mph. If you know of any info please IM me.