Save/Export ASCII to ASCII file

Hi all.

I have a U.S. ASCII file (.txt) that is input data for a IDL program I am using from a friend. The data are formatted in a very specific way (explicit format for ASCII files), such that moving just 1 character over will throw the IDL program off causing it to barf. I would like to overwrite his data with mine so the code is still acceptable, which I could do in a text editor. However, because there is so much data I would rather import the .txt file into Excel as a ASCII file, manipulate it, then export as a ASCII that is identical to what I started with except for the data values. I have tried exporting as a MS-DOS, .prn, Windows Formatted Text, etc. but when I open these columns have been shifted and characters are not where they should be.

Any idea on this one?

I have attached the original file which you'll see in a text editor has all columns neatly arranged. I just want to open this file in Excel, modify the values, and save it as nearly identical ASCII file.

Thanks much!
MC