Combining data in columns into one row.....

Hello,

First let me apologize for using a basic description as I am not an Excel power user. I am trying to combine column of "years" into a single row, for example:

Product Position Make Model Year Year End
MPN Back Make Model 1997
MPN Back Make Model 1998
MPN Back Make Model 1999
MPN Back Make Model 2000
MPN Back Make Model 2001
MPN Back Make Model 2002

I would like the formula to return:

Product Position Make Model Year Year End
MPN Back Make Model 1997 2002
MPN Back Make Model 1998
MPN Back Make Model 1999
MPN Back Make Model 2000
MPN Back Make Model 2001
MPN Back Make Model 2002

The other scenario is that there maybe times when years in the middle are skipped so the formula would need to "reset" itself as the 2000 year is "missing:"
Product Position Make Model Year Year End
MPN Back Make Model 1997 1999
MPN Back Make Model 1998
MPN Back Make Model 1999
MPN Back Make Model 2001 2002
MPN Back Make Model 2002

Basically I need to now that a part number fits 1997-2002 in one instance and 1997-1999 and 2001-2002 in a second instance.

Attached is the sample excel file, your help would be greatly appreciated.
Philip