[suicideneil]

Cant change to a truggy pinion as they have helical cut gears, you'd need to change both the ring and pinion gears- not sure if there are truggy ones that would be a direct fit for the savage diff cups.

Another option for a lower overall gear ratio would be to lock the truck into 1st gear instead of second, that'll allow you to have a lower overall topspeed using the same spurs and pinions you have now- same effect as using truggy gears instead of buggy ones. Not sure if thats a viable option for you, but it shouldnt be too techinally difficult if you have the parts of a fully functional tranny to play with.