i put a b&m shift improver kit in my 95 z28 but i lost 3rd and 4th everything looks fine but i found a 1in by 1/4 in metal cylinder that i have no idea where it goes help

 

[8D] was this something that came with the kit?? or maybe fell out of the valve body when installing the kit?? if the kit says to remove it or be careful this may fall out you may have a clue as to where it goes from the kit instructions. if not i think my factory manuals show trans schematics and maybe i can help if i know what exactly it looks like, sounds like a spool valve kurt

 

I'm curious where you found the part too. It sounds like one of the valves from out of the valve body.
Does your mystery cylinder have a couple of channels with cross-holes in it? It could be your 4-3 throttle valve?