Changing the front end, what RPO
 

changing the front end out in my 98 blazer what RPO tells me the gear ratio so I know if I have to change out the rear end too or if the donor has the same ratio saving me tons of work.

GU2:-:2.73
GU4:-:3.08
GU6:-:3.42
GT4:-:3.73
GT5:-:4.10

Not all ratios were available in all year models.

thanks.. I found the RPO on mine that says it is a GT4 G80 but for the life of me I dont think it ever kicked into posi mode.. the Donor Blazer I got for the front end has a RPO of GU6 so I guess i'll be switching out the whole rear end too.. or can i just change out the ring and pinion? would be nice if I could keep the posi and use the donor gears. I know I know... ( i'm a Gear ratio newby ) never had to work on them before though..