factory toyota pinons are color coated. if look threw the driveline yoke(or unbolt the driveline) the pinion will have a color from the factory. if i remember right pink was 4.10 and red was 4.3 but its been years, im sure there is someone on here that will know fer sure.
edit:
http://www.4crawler.com/4x4/4R_TechInfo.shtml toward the bottom it has the pinon colors
RUGER
