The shift lever will fit the bar-end "pod". Take a look at this PDF:
http://techdocs.shimano.com/media/te...9830628723.pdf
The important part is the "lever boss cover". Keep the one from the bar-end shifters. It's different from the ones on most downtube shifters. Its orientation needs to be correct, too- the fat tab should point down when you bolt it all together. If it doesn't, it'll index, but only for a couple clicks.
Also, tighten the center screw very tight.If it comes loose, it will allow the "friction/index" switch to fall between the two settings. This can ruin the shifter.