need a way to uninstall vbseo without lose google rank

Hello

i try to change my vbseo links but i will lose my pages in google

so i need any method to redirct the old pages to the default lonks

for example

i have this links

vb/t120.html

i need to redirect this link to

vb/showthread.php?t=120

i try using this code in .htaccess file

RewriteEngine on
RewriteRule ^t/?(.*)$ showthread.php?t=$1 [R=301,L]

but its give me 404 errpr page

please help

regards