Sort with combobox

I am uploading a sample inventory list. Each list is on a different sheet (not necessary, but useful in organization). The lists are from row 2 to row 35 on all of the lists. I am having trouble writing an equation to perform data validation, referencing information on different sheets.
It should be simple:
=INDIRECT(C5!C5)
That is what I tried. I used this because the sheets and lists are labeled the same. Also, I do not believe VLookup will work for autofilling if the lists are on the same sheet because vlookup looks up the leftmost column (right?) and the lists would be in separate column groups (ex: WeldYoke from A-D, YokeShaft from E-H).
edit: The data validation I was trying with the code was suppose to occur in B5:B19


Just some thoughts on my part. If I am making this too complicated, let me know.

OH! And for future reference, this is the BOM format we are looking at using. It is located on the SampleBOM sheet.