hello i have a 1998 gmc jimmy 4.2 4x4 can anyone tell me if all of the 7.5 differential covers with the ten bolt hole'* are the 3.73 gear ratio ???

you have to look at the rpo code sticker and look it up online. this is for a full size but you look in the glovebox:
GQ1 -- AXLE REAR, STD RATIO
GT4 -- AXLE REAR, 3.73 RATIO
GT5 -- AXLE REAR, 4.10 RATIO
GU4 -- AXLE REAR, 3.08 RATIO
GU5 -- AXLE REAR, 3.23 RATIO
GU6 -- AXLE REAR, 3.42 RATIO
G80 -- AXLE REAR, LIMITED SLIP (POSITRACTION)

thanks it helps alot

GQ1-STD Ratio. What is a standard ratio?

ive been told that just mean the standard level like not heavy duty

Ahhh. Gotcha. My *-10 has the GU6 and G80.

Usually the */T platforms have a 3:42, most of them have the G80 also.