gear question

[CJ_4]

i know this is probably a dumb question, but where do you find what gears and tranny you have. i'm guessin i got like maybe 3.43 gears. i run bout 2100 rpm at 70 mph. i know it's a dumb question, but i just can't seem to find it.
thanks for the help

[Hubert]

Look in glovebox or door jam for RPO codes thats what factory installed.

[trbankii]

Hubert gave half the information. After getting the codes out of your glovebox, take a look at something like this list - http://www.c2e.info/rpocodes/MODERNGMRPO.html - to see what they all mean.

[DennisG01]

This link might be a bit easier - it's from the "Member's Area":
http://www.thedieselpage.com/members/rpocodes.htm

[16gaSxS]

With my 3.42 I see about 2000 rpm @70 mph. The calculation works out to 1978 rpm @ 70 MPH. ;)

3.73 ratio with 245-75-16 tires calculate out to 2157 rpm @ 70 MPH.

[Patrick m.]

i used to know them off hand.... GU4= 3.08, GU6= 3.42, GT3= 3.73 GT4=4.10

[CJ_4]

thanks for all ya'lls help. i'll check it out next chance i get

[Craig M]

If worse comes to worse just use the old raise the truck, turn the wheel and count the revolutions of the wheel for one driveshaft revolution.