Gear Ratio

I just bought an 83 GMC Sierra and I'm trying to find out what the gear ratio is but i cant seem to find the matching code. I know they usually start with a G but the only G codes there are: G50 GQ1 G80 i tried to google it but couldnt find it. Here are all of my codes:

A01 A28
CD4 D45
E63 F59
F60 GQ1
G50 G80
J50 LE9
MX0 NL2
N41 N67
TT5 U35
U37 O58
V22 V31
V42 WB4
XBJ YBJ
YE9 ZBJ
ZY1 Z49
18D 29L

Also wondering if my stock 3.73 gears from my 2001 Silverado will fit in the 1983? They're both 10 bolt diffs.

Pull inspection plate and the gear ratio should be stamped on ring gear.
If not count ring gear and pinion teeth and post back or divide ring gear teeth by pinion teeth.

Pull inspection plate and the gear ratio should be stamped on ring gear.
If not count ring gear and pinion teeth and post back or divide ring gear teeth by pinion teeth.

But wouldnt i have to change out the diff fluid? It was just changed on the truck so is there any other way?

Count the driveshaft turns to turn the rear wheels one revolution.

GQ1 is "Standard Ratio". According to the post http://www.hotrodders.com/forum/rear-end-gearing-82449.html this meant 2.73 except when MM3 tranny was installed. This info is for 81 so it may not apply to yours.

You should post the ratio when you verify what it is.

//2000CAYukon