6 speed vs. 8 speed trans

[crash68]

How can I find out what the rear end is geared at?

Enter your VIN here: https://fcacommunity.force.com/RAM/s/equipment-listing
This will give you the build sheet for how your truck left the factory.

Chances are your Hemi truck is 3.92 geared, drive 73 mph on the freeway with the transmission in 8th gear, if your above 2K rpms it's 3.92 if it's less than it's 3.21.
3.55 was only available with either V6 or the 6spd trans Hemi

 

[Smbrownx]

Were both rear ends geared the same?
Probably not if 8-speed is downshifting.......most likely the 6-speed was geared 3.55 or 3.92 and the 8-speed is 3.21

Looks like both trucks are geared at 3.92. Both have 32 gallon tanks but this 8spd is getting at least 50+ miles less to the tank than the 5spd. Any ideas?

 

[crackerjack1957]

Looks like both trucks are geared at 3.92. Both have 32 gallon tanks but this 8spd is getting at least 50+ miles less to the tank than the 5spd. Any ideas?

Not sure what it could be.......8-speed suppose to be more efficient than the 5/6-speed.
Check the brakes......maybe caliper is sticking