The 1947 - Present Chevrolet & GMC Truck Message Board Network







Register or Log In To remove these advertisements.

Go Back   The 1947 - Present Chevrolet & GMC Truck Message Board Network > 47 - Current classic GM Trucks > The 1973 - 1987 Chevrolet & GMC Squarebody Pickups Message Board

Web 67-72chevytrucks.com


Reply
 
Thread Tools Display Modes
Old 09-29-2012, 05:49 AM   #1
C30trailerspecial
Registered User
 
Join Date: Sep 2012
Location: gold coast
Posts: 40
diff ratio

Iv got an 81 C-30 350 4 speed man with the big 14 bolt dually out back, Im just wondering what ratio this baby is and whats available to make it more highway friendly?
C30trailerspecial is offline   Reply With Quote
Old 09-29-2012, 08:15 AM   #2
Desert1957
Registered User
 
Desert1957's Avatar
 
Join Date: Apr 2009
Location: New Freedom Pa.
Posts: 1,335
Re: diff ratio

My ratio was 4.10 , I have friends who tow race car trailers and have switched to 3.73 , easier on the engine (RPM) didn't noticed any power loss towing.

Desert
Desert1957 is offline   Reply With Quote
Old 09-29-2012, 03:05 PM   #3
1985-GMC
Chevy Enthusiast
 
1985-GMC's Avatar
 
Join Date: Jul 2009
Location: Canyon Lake Texas
Posts: 2,024
Re: diff ratio

Is it a cab & chassis truck? If not then its probably a Dana 70 HD. A NV4500 swap would make it cruise a lot nicer.
__________________
Tony
1985 GMC K2500 restoration Project: Rust, White & Blue
1989 Chevy R3500 CC Cummins & 4X4 swap some day...
1989 Burb (D60, 14BFF, 12V, NV4500, NP205, 37" tires in progress)
1985-GMC is offline   Reply With Quote
Old 09-29-2012, 03:10 PM   #4
74 stepside
Registered User
 
74 stepside's Avatar
 
Join Date: Oct 2009
Location: SoCal
Posts: 815
Re: diff ratio

Most duallys are 4.10. If it is then, like stated above, a 3.73 will be the best answer.
74 stepside is offline   Reply With Quote
Old 09-29-2012, 04:43 PM   #5
C30trailerspecial
Registered User
 
Join Date: Sep 2012
Location: gold coast
Posts: 40
Re: diff ratio

I was actually thinkin 3.7s, a buddy has those in his F truck with a 31" tall tyre, seems to tow good
C30trailerspecial is offline   Reply With Quote
Reply

Bookmarks


Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 12:36 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Copyright 1997-2022 67-72chevytrucks.com