Ok so I was on my way to work this morning and noticed my RPM's. It appears to run 1975 RPM's at 65 MPH in OD. I have the 392 rear end with 31/10.5/R15's.

1. What does the stock D run with the same gears and tires?

2. Also what about the I believe (352's) run at the same RPM's?

 

I found out it varies from Durangos to Durangos on year models.

1. My 2000 R/T with 3.92 gears, I hover at almost 2100 RPM's. I seen Last of R/T's took a pic where his 2003 R/T hovers at 70 mph at 2000 RPM range. So I don't know if the newer 1st generation Durangos may have a taller OD gear. At 70 MPH on my Durango, it hovers at 2200 rpm's. Would love to hover at 2k so my 5.9 won't work so hard.

Here is the link where we previously discussed about cruising engine rpm's at cruising speeds with PICS!

https://dodgeforum.com/m_133746/mpag.../tm.htm#136364

 

My 5.9L with 3.55 runs about 1800-2000 RPM at 60-65MPH in OD. I have the factory 31x10.5R15s on there for now.

What kind of milage are you getting with 3.92s? I am thinkng I may need to switch to 3.92 or 4.1 gearing if I move to 33x10.5R15 BFGs.