The Classic Mopar 5 Speed transmission has a few, but very significant differences from the Keilser offerings. First off, they use the same tranmission from Tremec. This is where differences start, the shifters on both kits are relocated to come up in the correct factory floor location. The shifter on the Classic unit is a McLeod Slik-Stick, a very nice piece that uses a ball and socket system. Keisler using the stock billet unit that the transmission ships with and uses a linkage to the get to the external shifter rail. Classic has move all the external shifter rail parts forward to remove the potential for drive line vibration. The length of the yoke exiting the tail housing is critical in minimizing drive line vibrations.
The "extra" parts that you do not see on Classic's website are available on the open market. The reason that they do not stock these parts is the cost of shipping to California, warehousing and such that drives up the cost. Classic will provide you with a list of the parts that are available on the open market that you can purchase directly and save yourself money.
