A support pin assembly for supporting and/or locating a fixture on a tooling plate is provided. The support pin assembly includes a stanchion with a bore configured to secure the support pin assembly to a locating surface on the tooling plate. A sleeve is included within the stanchion bore, such that the sleeve is infinitely adjustable between two positions and lockable with respect to the stanchion. The assembly additionally includes a locator pin engaged at a first end thereof with the sleeve, and configured to mate at a second opposing end thereof with the fixture. Furthermore, the assembly includes a stopper pin operatively connected to the sleeve and configured to selectively extend and retract relative to the locator pin. The locator pin is free to displace relative to the locating surface when the stopper pin is retracted and is blocked from displacing when the stopper pin is extended.