I think you are asking about V-gate or Z-gate shifters, also called vertical gate shifters. Lift the small "t" on the shifter and slide it forward for first, straight back for second, straight forward for third, straight back for 4th (forward again for 5th, if necessary!). Neutral is in the center, and reverse has its own short lever that can only be moved when the shifter is in neutral.
They are available for toploaders, Jerico and Richmond transmissions, but I have never seen any for tremec. I have looked, but not found them. This is possibly because of the shifting rod arrangement used by tremec, while toploaders and richmonds have external linkage.
Check the site
http://www.g-forcetransmissions.com/shifter_price.asp
they have the shifters. I would recommend going to swap meets to see if you could get one to "modify" for a reasonable price.
They are illegal in most states for street use. I had one in a Ch*vy and loved it! Never missed a gear.
Automatic transmissions have shifters that simulate the v-gate look, but there is nothing like it.
tj61@juno.com