Starter makes clunking noise

[Ethan341]

After putting a fresh clutch in my truck the starter has been giving me lots of troubles lately...It starts starts occasionally fine but most of the time it makes a terrible clunking noise from the starter. I swapped starters with it from another truck and tried every combination of shims. Don't really know how to describe the noise, its not a dead battery clicking noise but a clunking sound and the engine still turns over just slowly when it happens. After searching around the internet I couldn't find any solutions so anybody have any ideas of what could be happening?