Depends on the shifters. I know the modern Shimano bar end shifters pods will accept just about any DT shifter that fits on the standard post, but I don't think they go back as far as 6 speed indexing, the fewest I've ever seen is 7 speed. If its the suntour accushift 6-speed bar-end shifters I'd be a little more skeptical about mixing and matching parts. The two sets I've had of those were very finicky just by themselves.