There are two mainstays on the Kansas City Chiefs offensive line and those are LT Eric Fisher and LG Ben Grubbs. Those two have consistently been the first team players at their positions without any rotating in and out (save the occasional look at Donald Stephenson at LT). Fisher and Grubbs are almost assuredly your starters at those positions.
It's every other spot on the offensive line that's a concern. The Chiefs have position battles at center, right guard and right tackle and they have begun to mix it up with various offensive line combinations.