if you ever hit that dead spot between 3-4 real hard (which aint to hard to do) you will bend the aluminum 3-4 shift fork Tremec addressed this problem with a cast 3-4 fork, however all six speed trannies are the same internally, including the viper one, the only difference is making one fit into the other chassis, now with that said the viper comes with a steel 3-4 shift fork which IMO is better than cast iron so if it is tweaked and you have to replace it anyways go with the steel one, you can pick it up at any Dodge dealership and its a direct replacement, you will also have to replace the synchos and blocking rings too, if you find out that the stocker is still good, throw it out anyways, because its just a matter of time before it will be toast, when mine went out it grinded real bad into 3 and 4, and would have to be forced in gear, and then it would start to spit it out of gear, once replaced, it felt like a whole new tranny, hope this is what you were after, good luck