so I know I need two O-ring for the coolant change..

the radiator drain plug and the air relief plug one..

ARE THEY THE SAME SIZE?
21481-89900 part number?

Also, where in the interweb can I buy this? the best price..??

 

they are the same size...and you can reuse them with no problems.

 

I got mine from:
infinitipartsusa.com
which is the parts website for Infiniti of Scottsdale. You can also try:
grubbsperformanceparts.com/partlocator/
which is the parts site for Grubbs Infiniti in Dallas

I've never had a problem dealing with either of them, and both are known for treating their customers well.

 

cool cool.. thanks fellas..

ordered..