There are some visual signs but even those parts get swapped around. Plus installing the gear sets from the lower ratio 3 spd( 10 spline) into the stronger case of the 4 spd (16 spline) is very common. In regards to the ToyBox we need to know if you have a 10 spline or a 16 spline input gear. We only offer a 10 spline out put shaft so with a 16 spline gear set we provide a new 10 spline gear to convert the 16 spline gear set. You will probable need pull the PTO cover and count the teeth on the input gear so we can find the ratio and remove the rear cover to loosen the nut and slide the PTO gear or spacer to count the output shaft splines.
