If the top of the UV looks like this, your lamps are the 005-422-9017. Click Here
NOTE: If you need to replace the top and bottom lamp retainer, you can purchase the whole assembly for one, two or three lamp systems. However, in most cases, only the lamps need to be replaced.
If the top of the UV looks like this, your lamps are the 005-422-9005-00. Click here
NOTE: If you wish to upgrade your lamps to the newer style, you have the option of purchasing the Ultra UV2 lamp assembly for one, two or three lamp systems.
Paramount recommends upgrading to the newer lamps, as they running cooler and help avoid degradation of seals that can create leaks.