The original type of reverse manual valve bodies did not apply the band that holds the low/reverse drum. By holding the low/reverse drum along with the sprag increases safety from a sprag failure which would spin the high gear clutch drum over 10,000 rpm and it could come apart (explode) and could come thru the floor and oil the tires. Bad deal. The sprag on the old valve bodies are the only thing holding you in first gear. If you don't follow the correct procedures they can come apart. If you are able a good drum is a good idea but personally if you are making 400hp or so and use the good valve body I've had no problems.