Find and Paste Apple Script - replace

Question

I have found an AppleScript below that finds and replaces... However instead of replacing with "401" in this case I want it to replace with what is on the clipboard.
So I am trying to put something like: set stringToReplace to keystroke "v" using command down...But that doesn't work (Expected end of line, etc. but found identifier.)
Here is the code:
on run {input, parameters}
set stringToFind to "404"
set stringToReplace to "401"
set theFile to choose file
set theContent to read theFile as «class utf8»
set {oldTID, AppleScript's text item delimiters} to {AppleScript's text item delimiters, stringToFind}
set ti to every text item of theContent
set AppleScript's text item delimiters to stringToReplace
set newContent to ti as string
set AppleScript's text item delimiters to oldTID
try
set fd to open for access theFile with write permission
set eof of fd to 0
write newContent to fd as «class utf8»
close access fd
on error
close access theFile
end try
return input
end run

Answer 1

Solved the issue:
All I needed to do was add: the clipboard after set stringToReplace to
on run {input, parameters}
set stringToFind to "404"
set stringToReplace to the clipboard
set theFile to choose file
set theContent to read theFile as «class utf8»
set {oldTID, AppleScript's text item delimiters} to {AppleScript's text item delimiters, stringToFind}
set ti to every text item of theContent
set AppleScript's text item delimiters to stringToReplace
set newContent to ti as string
set AppleScript's text item delimiters to oldTID
try
set fd to open for access theFile with write permission
set eof of fd to 0
write newContent to fd as «class utf8»
close access fd
on error
close access theFile
end try
return input
end run