Installing rear from leaf truck to coil truck - The 1947 - Present Chevrolet & GMC Truck Message Board Network

krue · 08-30-2007, 05:37 AM

What do I need to put a rear end from a late 70's (12 bolt) under my 70 GMC with coils? I'm putting a 200-4R in my truck and I'm currently running the stock 3.07 rear and I think I'll wind up with the rpm's too low on the hiway, plus I want a little more bottom end. I've got a 3.42 rear end given to me (thanks Gman!) that I think will be perfect but it's set up for leaf springs.

glock35ipsc · 08-30-2007, 11:52 AM

Other than cutting the spring perches off of the new rear, and cutting off and welding on the trailing arm perches from the old rear, you will probably need one of the longer, adjustable pan hard pars since I doubt the new rear will have the lug stick up from the center section.

mvfd70 · 08-30-2007, 12:03 PM

If you dont want to cut the old perches off the old axle. Early Classic sells new axle saddles. Do a search on their site for Rear Axle Saddles. And like said above, you'll need to do something about the pan hard bar

elf w/capital T · 07-19-2013, 06:30 PM

Has anyone done a writeup? What about the angle of the pinion before welding on the new saddles?

jmorri34 · 07-19-2013, 10:05 PM

I just did this to my truck and put in a 9 inch. I have a build thread but not sure if it will help. Go into the build threads on this page and go to the "ole 69er" and you will see what we did!

jmorri34 · 07-19-2013, 10:06 PM

The "Ole 69er" ( 1 2 3) in the threads page is the one I did, couldnt figure out a way to put the thread on here but at least youll know what it looks like

elf w/capital T · 07-20-2013, 07:58 AM

Jmorri, thanks!!

jmorri34 · 07-20-2013, 11:31 AM

Quote:

Originally Posted by elf w/capital T

Jmorri, thanks!!

Sure no problem, if you have any questions just let me know and if I can help I'll do it!!

08-30-2007, 05:37 AM	#1
krue Designated A-hole! Join Date: Mar 2003 Location: South Mississippi Posts: 36,450	Installing rear from leaf truck to coil truck What do I need to put a rear end from a late 70's (12 bolt) under my 70 GMC with coils? I'm putting a 200-4R in my truck and I'm currently running the stock 3.07 rear and I think I'll wind up with the rpm's too low on the hiway, plus I want a little more bottom end. I've got a 3.42 rear end given to me (thanks Gman!) that I think will be perfect but it's set up for leaf springs. __________________ "If it ain't broke, fix it 'til it is!" Being stupid ain't illegal. We're Still Debt Free Except for the House!!! www.daveramsey.com 70 GMC SWB Stepside project "Green Booger" soon to be 6.0l/4l80e 93 S-10 "Poppaw's Truck" Last edited by krue; 08-30-2007 at 05:39 AM.

08-30-2007, 11:52 AM	#2
glock35ipsc Next project: 1970 K10 Join Date: Feb 2004 Location: Fort Collins, Colo 80524 Posts: 6,685	Re: Installing rear from leaf truck to coil truck Other than cutting the spring perches off of the new rear, and cutting off and welding on the trailing arm perches from the old rear, you will probably need one of the longer, adjustable pan hard pars since I doubt the new rear will have the lug stick up from the center section. __________________ *Bob* 1970 Chevy K10 LWB "Goldie" 350/TH350 *next project!!* 1981 Chevy C10 LWB 355/TH350 - My son's truck LS SWAP FORUM! Tons of LS swap info here! PLEASE CLICK HERE TO SUPPORT THE GREATEST BOARD ON THE NET! CLICK HERE FOR THE FAQ INDEX by KRUE

08-30-2007, 12:03 PM	#3
mvfd70 Registered User Join Date: Jan 2007 Location: Opdyke, IL Posts: 775	Re: Installing rear from leaf truck to coil truck If you dont want to cut the old perches off the old axle. Early Classic sells new axle saddles. Do a search on their site for Rear Axle Saddles. And like said above, you'll need to do something about the pan hard bar __________________ 1978 Chevrolet Silverado 3/4 ton 400 small block. 2000 F-250 Powerstroke 2002 GMC Yukon Denali XL

07-19-2013, 06:30 PM	#4
elf w/capital T Registered User Join Date: Feb 2011 Location: North Carolina Posts: 993	Re: Installing rear from leaf truck to coil truck Has anyone done a writeup? What about the angle of the pinion before welding on the new saddles?

07-19-2013, 10:05 PM	#5
jmorri34 Registered User Join Date: Sep 2012 Location: Spring, Tx. Posts: 479	Re: Installing rear from leaf truck to coil truck I just did this to my truck and put in a 9 inch. I have a build thread but not sure if it will help. Go into the build threads on this page and go to the "ole 69er" and you will see what we did!

07-19-2013, 10:06 PM	#6
jmorri34 Registered User Join Date: Sep 2012 Location: Spring, Tx. Posts: 479	Re: Installing rear from leaf truck to coil truck The "Ole 69er" ( 1 2 3) in the threads page is the one I did, couldnt figure out a way to put the thread on here but at least youll know what it looks like

07-20-2013, 07:58 AM	#7
elf w/capital T Registered User Join Date: Feb 2011 Location: North Carolina Posts: 993	Re: Installing rear from leaf truck to coil truck Jmorri, thanks!!



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