Hi Mike,

I believe I figured out your lookup but had to move the long list of
customers to the right of the long-list of part numbers.

=IF(ISNA(VLOOKUP(F15,D15:E19,2,0)),VLOOKUP(F15,B15 :C24,2,0),VLOOKUP(F15,D15:E19,2,0))

Where F15 is the part number to look up.
D15:E19 is the short part# list and different customers.
B15:C24 is the long part# and customer list.

So, if the part# in F15 is found in the first lookup you get a different
customer from the short list.
If the part# in F15 is not found in the first lookup, it returns ISNA and
the lookup goes the long list.

I can send my sample work sheet if you want to help you figure it out.

HTH
Regards,
Howard

"Cube Farmer" wrote in message
...
Hello, I have a column of customers (A) and a column of Part #s (B).
I also have a short column of part #s (C). If a part in (B) is found in
(C),
I want it to change to a totally different customer, say it is in (D). If
it
doesn't match I want it to stay the same.
Thanks for looking.
Mike