One of the major challenges for typical opto-mechanical assemblies is that they require multiple degrees of freedom with large travel (several millimeters) but very small (sub-micron) resolution. After adjustment, assemblies must be stable to a few nanometers to survive environmental and mechanical shock over a lifetime of use. Using parts with engineered mating surfaces, we have developed a low-cost and robust set of components with demonstrated sub-50-nm adjustment resolution and comparable stability after multiple environmental stress events. For this work, we have adopted -30 to +70 C temperature cycling and 10 G (15 ms) half-sine shock as our environmental qualification standards. We apply the methodologies of reliability testing learned for Telcordia qualification of passive fiber optic components to opto-mechanical components and assemblies for capital equipment instruments. Demonstration of sub-50-nm resolution and stability for our developed opto-mechanical components requires a suitable test stand, which we have developed using scanning knife-edge beam profilers and a highly-repeatable kinematic loading base with a built-in reference. We use these test results to develop system error budgets in design and manufacture based on component, assembly, and measurement tolerances. The developed opto-mechanical assemblies have been demonstrated to have sub-50 nm stability in laboratory and field tests.