Change truck rear end change ratio

[Skerndne]

I have a single axle mack MS 200 and I want to change Rear end. Do I have to find a rear end out of a diesel or can I use a rear end out of a gas truck or if the gear ratio is the same it makes no difference. My ratio is 5.10 should I look for 5.10 or high or 5.10 or lower. What will a high one do and what will a lower one do to my truck.

I have a 5 speed trans with a Ranult 6 cyl diesel. If I go with a lower grar ratio will I loose power in 1st gear.

 

[sewmun]

I'm guessing you want a better road gear?If so it would also help to know what trans you have some have an overdrive gear.
So to answer your question a 3.70 would be better on the road.I have a truck that came a 4.10 ratio && @ 65 the rpm was approx 3400 rpm that's alot more than I wanted to run.So I found the tag on the rearend called a truck parts yard & they had a pig (center section) with a 3.42 so I bought it,pulled ythe axles & my son & I put it in so now @ 65mph the rpm is 1800
And I'm getting around 11 mpg.

 

[Skerndne]

thanks for your input what did the change do to your low, 1st gear I don't want to loose power in 1st.

 

[x06col]

Any time you change your final drive ratio you will either gain or loose power in ALL gears!! Why are you so concerned about "low" gear? I'd be more concerned about "high" gear negotiating inclines. Specially with that Renau.

 

[Skerndne]

I run mostly around the country side near my home hauling dirt fill, top soil and fire wood. 1st gear needs to be strong as i am off road a lot. The Renault pulls great when I do run it up to 65 mph mine is the 6.20 214 hp.