Yamaha stopped using model years in 2005. In 2005 your motor would have been a 50TLR
D. The letter D denotes it as being a 2005 model year motor.
A 50TLR could have been made in 2005 all the way up to 2009 when they were discontinued here in the USA.
As noted, there should be a placard on the side of the motor that indicates the month and year of manufacture. You use that to find the correct parts catalog for the specific motor.
Another way is to simply type the engine ID into the search box at Yam's website. It will then take you to the parts catalog for the specific motor. See example below. This indicates the motor was made during or after April 2007 but before April of 2008.