If you put in C1 the word "Truck #:" and then use D1 for what truck # you
are looking for, this will be your query area.  In C2, type the words "Last
Time Stamp:" and in D2 type the following formula:
 =LOOKUP(2,1/($A:$A=$D$1),$B:$B)
This will give you the last time stamp for the truck # you specified in cell
D1.  I recommend you shade cell D1 in a turquoise and put a light border
around it (like a solid dark gray line) so people are drawn to it and know
that is the only place they have to type in their query.

You could also write a macro that brings up a message box asking you what
truck # you want to search for and gives you the result in another message
box, but my solution above is the simplest and avoids security issues with
macros.
Cheers!
KC Rippstein

try this array formula which must be entered using ctrl+shift+enter
=MAX(IF(A2:A22="mytruckcode",B2:B22))
or
=MAX(IF(A2:A22=c2,B2:B22))