Don---I thought that you new that spring loaded ball plungers were commercially available, or I would have mentioned it to you. I use them all the time in machinery I design, so ya know how it goes ---I have known about them for years, so I assume that everybody else does too. One word of advice----get one with a really strong spring. From the pivot point on your shifter to the detent ball is only about 1 1/2", yet the shifter lever will be about 18" long from the pivot point. That gives you a mechanical ratio of 12:1, so you should have no problem overcoming a really strong detent spring.---How are you going to design the lock-out gates???? The spring detent ball will hold the shifter in position for normal driving, but without a lock-out gate, the shifter will still move if it gets bumped with a knee, or under real hard acceleration. This could spell disaster. The Gennie shifter must be manually rocked to one side to disengage the lockout gates, thus require no push-button. The Lokar units have a sprag which is engaged with the lockout gates at all times unless you manually depress the shift button to allow a shift. (actually they have no lockout gates between drive, drive 1, and drive 2, which makes sense, but they don't have a lockout gate between drive and neutral either---as many street racers with blown-up engines can attest to).