98 s-10 ABS issue

friend of mine has a 98 s-10 like mine with the 2.2L manual trans, ABS is the main issue though. the master cylinder bleeder valve on the ABS modulator is leaking. have looked everywhere for just the bleeder valve, even gmpartsdirect.com, and all i can find is the whole modulator valve. anyone have this problem before and find just the valve, or is the new modulator valve the only answer? don't want to go the junkyard route for brake/ABS type parts of this nature, and the only other option aside from replacing the modulator is to plug the bleeder hole with silicone, super glue, or something of the like. any ideas?