Please tell me what parts interchange between the 2.45/2.25 vice 2.71->up 8 1/4 axle

Notanova73 said
side note should I worry about some of these gear sets that say 76 and newer?and what’s with 2 or 3 series

2 series refers to 2.xx gears and carriers and 3 series refers to 3.xx gears and carriers. The 2.94 carrier is considered to be in the 3 series carrier set I believe.