1969 GMC SWB Rear End swap in DFW??? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

tx69gmc · 04-25-2006, 11:49 PM

Hey all-

I am wanting to potentially swap the rear end in my 69 GMC SWB. Is it correct that I can use anything from 73-87 due to the fact that my truck is already set up with leaf springs. Posi or locker would be nice as well. I am going to be converting to 700R4 as well so what ratio is recommened for mild performance and good streetability? Thanks

wibilly · 04-26-2006, 12:01 AM

from what i unerstand front axels bolt in rears the spring perches must be relocated as far as ratio i wouldn't want cruse rpm in overdrive to be less than 2000 rpm and if using a higher than stock stall converteri would be sure and keep cruse rpm atleast 200 rpm above stall speed

rauto13 · 04-26-2006, 12:45 AM

I have 3.73 gears in a posi with a 700R4. My RPM at 70 mph is 2400 RPM. I personally think it is an ideal cruise RPM.

Longhorn Man · 04-26-2006, 05:13 AM

yeah, you don't want to go under 2000 RPM for cruise speed. 2200 - 2400 is ideal.
If you get a lock up converter, then stall speed isn't nearly as important since it'll go into lock up and there will be 0% slippage.

04-25-2006, 11:49 PM	#1
tx69gmc Registered User Join Date: Nov 2005 Location: Denton,TX Posts: 61	1969 GMC SWB Rear End swap in DFW??? Hey all- I am wanting to potentially swap the rear end in my 69 GMC SWB. Is it correct that I can use anything from 73-87 due to the fact that my truck is already set up with leaf springs. Posi or locker would be nice as well. I am going to be converting to 700R4 as well so what ratio is recommened for mild performance and good streetability? Thanks

04-26-2006, 12:01 AM	#2
wibilly Senior Member Join Date: Nov 2005 Location: northwestern wi Posts: 2,111	Re: 1969 GMC SWB Rear End swap in DFW??? from what i unerstand front axels bolt in rears the spring perches must be relocated as far as ratio i wouldn't want cruse rpm in overdrive to be less than 2000 rpm and if using a higher than stock stall converteri would be sure and keep cruse rpm atleast 200 rpm above stall speed __________________ common sense isn't so common anymore

04-26-2006, 12:45 AM	#3
rauto13 saving one more Join Date: Sep 2005 Location: Pryor Creek, Oklahoma Posts: 3,066	Re: 1969 GMC SWB Rear End swap in DFW??? I have 3.73 gears in a posi with a 700R4. My RPM at 70 mph is 2400 RPM. I personally think it is an ideal cruise RPM. __________________ 72 Chevy longbed - now for parts 69 Chevy short fleet - needing some love 70 RS Camaro - needing more love driver - 96 GMC X-cab

04-26-2006, 05:13 AM	#4
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	Re: 1969 GMC SWB Rear End swap in DFW??? yeah, you don't want to go under 2000 RPM for cruise speed. 2200 - 2400 is ideal. If you get a lock up converter, then stall speed isn't nearly as important since it'll go into lock up and there will be 0% slippage.



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