idlewildranch

how can i find out what gears and tranny are in my truck? w/o opening the diffs, is there something in the vin# or????? my truck is a 03 2500 cummins,short box, automatic

annabelle

Speed at 1800 RPM?

idlewildranch

i wanting to say at 65 mph the tach says 2200,maybe 2000

annabelle

4:10's. Mine is at 65 at 1800 RPM.

1985cucv

yeah sounds like 410's look in the glove box i think mine said what gears i have

idlewildranch

cool those are good gears for pulling

michiganracer2

Hmmm. My speed at 65 = 2000 RPM and I have 4:10s.

WhiteMule

With 4.10's, 31.6" tires @65 MPH=1955 RPM.
Here is a neat little RPM calculator for you. Use .69 for transmission final gear ratio on a 48RE auto.
http://www.csgnetwork.com/multirpmcalc.html

WhiteMule

I believe the final gear for a NV5600 is .73. Do not know what the other 6 speed manual final gear is though.

annabelle

I have stock tire (265's), I have 3:73's. At 1800 RPM I'm at 65 MPH.

WhiteMule

Did you try the little calculator above? Stock tires =~31.6" x 3.73 x 65MPH and .69 = 1779 RPM from the calculator. So that is real close.

annabelle

Thanks for the formula.

idlewildranch

i have 315 17s wa 9 in wheel, level kit,

WhiteMule

If you are going to use speed and RPM to tell ratio, the first question is--Have you corrected the speedometer for the larger tire size? If not, the calculations are somewhat irrelevant. Assuming you have, 315/70/17 BFG are ~34.4", 48RE auto tranny (.69),at 65MPH, with 3.73 = 1634 RPM, with 4.10 = 1796 RPM. If you have not corrected the speedo, these RPM's would be fairly close at 60 MPH shown on the (uncorrected)speedo for each ratio respectively.

idlewildranch

ive corrected the speedo