Tippmann part numbers 02-20 v2, 11736, and TA02036 all refer to the same sear spring. This part was also branded as a US Army sear spring using those same part numbers.
That spring has been discontinued, but it has a direct replacement. The part number history went from 02-20 to 02-20 v2 / TA02036 / 11736, and now back to 02-20 / 11812.
When you order from this page, you will receive a Tippmann 02-20 Spring.