ive been looking to upgrade to a 4.10 gear ,,and in the used parts section a few posts say the gears are for a 3 series carrier or 2 or 1 something like that ,,,what exactly does that mean,,and how can i find out what carrier i have in my car?

 

Assuming you still have the factory 10 bolt, you would have a 3 series carrier. The F cars came in either a 2 series or 3 series. Typically 3.08 and "numerically lower" were a 2 series carrier and 3.23 and "numerically higher" were a 3 series carrier.
If you watch, they do make gears, such as a 4.10 for a 2 series carrier.
That is a first time hearing ,for me, as far as the first number of the ratio being the series number of the carrier. I can't find any info on it that confirms that but with a gear ratio of 3.08, that sorta disproves that. Like I said, I never heard that before.