Detroit 60 series RPM range

This what am guessing is my current setup

 

22.5LP tires on there?

 

Never mind saw your post a page back

 

Ya, bud...
there is no such thing as a "regular" 10 speed transmission. It is either a direct drive(meaning 1:0 to 1:0). Or it is an overdrive transmission( in this case 1:0 to .74)

In your spicer road speed calculator screenshot you showed .800 for a ratio. There is no such thing. It would be either 1.0 or.74.

Look on your door post tag for the rear end ratio.

If it doesn't list it then crawl under your truck with a rag and a can of engine degreaser and look at the tags on both the rear ends and your transmission. Bring the numbers back here and I'll help you with it.

Just because some guy told you they "might be" 3.70's doesn't make it so. The tranny was changed out, the rears could have been also. In the last year I've swapped out my transmission and my rears...so the door tag is now inaccurate.

do a visual of the components , then come on back with your numbers. We'll help ya.

 

I have a question if anyone could please help, recently got a 2005 classic 14l Detroit, 13sp 3.55 ratio. Engine was overhauled, Egr deleted, and got a rebuilt transmission and new clutch just recently as well. But whenever i try to shift over 1400 rpms on gear 7h or let my rpms drop less than 1200 on gear 8h the engine goes into like a neutral mode and loses all power for like 3-4 seconds, engine starts revving up and down by itself and even if I step on the throttle it has no response. Then after like 3-4 seconds, it goes back to normal and It regains power. It only does it in those 2 particular gears and those exact rpms, and it started happening after the delete. Thought it was the transmission and it was replaced, still having the same issue

 

Will it hurt my 12.7 to cruise at 2000 rpm?
I have a 10 speed trans now and 370 rears.
Truck used to have a super 10 before I got it.
So the rpms may not have been this high

 

Nope it won't. You many not like the fuel mileage Lol but it's fine. It'll burn more fuel but it's actually less stress on the motor compared to if you lugged at 1200 rpm all the time

 

Before you get in, slam the door on your hand. Then you'll be pissed off and ready to operate that DD.