In GM 6L90 transmissions, the low/reverse sprag elements, end caps and retainer plates are prone to wear, while the race is often unaffected. This results in a bind-up going into 2nd Gear or a 1-2 flare. Sonnax low/reverse sprag rebuild kit 104642-90SK allows replacement of the caps, elements and retainer plate without the expense of buying a full sprag assembly.