This has been covered many times. Get Marz to send you the cartridge and top cap parts for the Super T for the same model year as your Jr. The exact year model probably isn't critical, but hey, why risk it...Marz should be able to send you the right cart. Your springs will work with the new cart. There is somewhat of a debate on running one or two Super T carts when doing this conversion. I ran two on mine, but I did it a long time ago on an '02 Jr.T. If I did it again, I'd just install one Super T cart and disable the SSV Jr.T cart that was left in the fork. I think leaving an unmodified SSV cart in one leg will still result in some compression spiking...which is what you're trying to do away with.