Stocking Matrix Replace NOT BLANK cells

[treznorse]

I have a matrix type spreadsheet with location numbers in column A and item numbers in Row A. Anywhere there is an item/location relationship there is a value (the forecasted sales units). I would like to replace only these values with the item number (also the column header in this case). I'm assuming there is a simple IF or ISBLANK solution, but I'm having trouble finding it.

Any help is appreciated!

Thank you!