K30 Downgrade to Cummins Project - The 1947 - Present Chevrolet & GMC Truck Message Board Network

jbclassix · 01-13-2015, 04:28 PM

My bone stock cummins tows just fine in overdrive with 3.55s. I think you'll want the 3.73s. We ran an '05 10.5 AAM on the 82 frame for my brothers crewcab. We had to relocate perches and shock mounts. I've also noticed the limited slip GM uses now (still has the RPO G80) is a different and more reliable design.

Vintage Windmills · 01-13-2015, 05:53 PM

Quote:

Originally Posted by jbclassix

My bone stock cummins tows just fine in overdrive with 3.55s. I think you'll want the 3.73s. We ran an '05 10.5 AAM on the 82 frame for my brothers crewcab. We had to relocate perches and shock mounts. I've also noticed the limited slip GM uses now (still has the RPO G80) is a different and more reliable design.

Cool. Do you know when the g80s improved? Also has anyone been able to harvest the perches and reuse them without destroying them or the axle? In the past, I hhaven't been able to save both but maybe a clean torch tip would allow it but I'd be nervous operating that close to the axle tube. Got a good source for heavy duty perches that fit these sumo

axles?

jbclassix · 01-13-2015, 06:47 PM

The 11.5 AAM has the different limited slip. As for the perches, ditch the stock crap. I know it's a more abusive environment, but the government trucks in our fleet needed the perches built up from wear. They are rounded on the edoes and allow for more movement. I wasn't happy with the aftermarket ones my brother bought either. I would have rather made my own. I'll be running a ladder bar setup on his for added strength

01-13-2015, 04:28 PM	#1
jbclassix Junk Yartist Join Date: Jul 2009 Location: Greeley, CO Posts: 2,203	Re: K30 Downgrade to Cummins Project My bone stock cummins tows just fine in overdrive with 3.55s. I think you'll want the 3.73s. We ran an '05 10.5 AAM on the 82 frame for my brothers crewcab. We had to relocate perches and shock mounts. I've also noticed the limited slip GM uses now (still has the RPO G80) is a different and more reliable design. __________________ -Jeremy YOU ONLY FAIL IF YOU STOP TRYING 70 Crew Cab Build Link 70 GMC Suburban 4X4 build thread 95 Yukon Daily Driver Rebuilding an NP205

01-13-2015, 06:47 PM	#3
jbclassix Junk Yartist Join Date: Jul 2009 Location: Greeley, CO Posts: 2,203	Re: K30 Downgrade to Cummins Project The 11.5 AAM has the different limited slip. As for the perches, ditch the stock crap. I know it's a more abusive environment, but the government trucks in our fleet needed the perches built up from wear. They are rounded on the edoes and allow for more movement. I wasn't happy with the aftermarket ones my brother bought either. I would have rather made my own. I'll be running a ladder bar setup on his for added strength __________________ -Jeremy YOU ONLY FAIL IF YOU STOP TRYING 70 Crew Cab Build Link 70 GMC Suburban 4X4 build thread 95 Yukon Daily Driver Rebuilding an NP205



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