What is the difference between Equa-lok,Trac-lok,True-Trac,Detroit Locker,?. I have a 69 mach 1 351 2v 3spd and I want to make it a Posi traction.  

IIRC, the Equa and Trac are similar and differ in the number of installed plates or some such.  A Detroit Locker uses cogs and not clutches to lock the axles together for straight line running.  The clutch types use springs and shims to basically create a bind to let the axles turn together, yet slip in a turn.  For a street car, a clutch type is fine.  Just be aware that if you take it to the strip, you can fry a clutch type real quick if you are not careful in the burnout.  

Thanks for the info Falcon67, Information very useful. I appreciate it.    

I have used both the Detroit Locker and Traction Lock (clutch type) units. I have a Traction Lock in my 69 428 car right now and find it very satisfactory for the street.  Sometimes the Detroit Lockers are a little to rough on the street they can make some noise and often jerk when they lockup in a lightweight car they can sometimes cause the frontend to push.  

A true DL, like the NASCAR units sold on eBay, will do that.  For a long time, I ran a Trac-tech "soft locker".  The Soft locker was tuned with springs and it almost never made any noise.  As for a push - yes, you best respect a true locker.  If you're used to having a bit of fun squirreling around the streets, you'll have to check up with a locker in the back.  You stab the gas with a locker and you best be pointed where you want to go because when the cogs lock up you are going there.