1990 Crew Cab Dually (R3500) - The 1947 - Present Chevrolet & GMC Truck Message Board Network

TravisMartin · 10-03-2009, 06:43 PM

I recently got this truck in somewhat poor shape and am trying to bring it back. It's a square body, so I asked essentially the same questions in the 73-87 forum, but got to thinking that mechanically it is the same as a 1990 C3500, so thought I'd ask here too.

It's a 454 with TH400; I can't find where the oil pressure sender is supposed to be (has had an aftermarket mechanical gauge installed) and I want to put it back stock. If I knew where the sender is supposed to be I should be able to find the wire.

I'd really like to convert it to a 4L80E also. I'd like to do this with factory parts as if it were a 1991 model. I assume the transmission is controlled from the ECM? If so, I should be able to do this with a 1991 ECM and harness, assuming I can find one...

Any help will be greatly appreciated.

Thanks,

Travis

ChevLoRay · 10-03-2009, 09:11 PM

Welcome to our Forum! I don't have the answers you seek, but I'll be glad to keep an eye out and help direct you to the right place if this doesn't work out.

BLE 'BURBAN · 10-09-2009, 01:44 AM

The O.P.Sending Unit should be installed just above the oil filter on the drivers side of the block.
Converting to an overdrive tranny will require shortening the driveshaft, as well as swapping out the main computer and the harness both under the hood and under the dash with one from a donor vehicle that has what you're after like a suburban, blazer or another crewcab if you can find one. Also you'll want to swap out the "PRINDLE INDICATOR" with a "PRINODLE INDICATOR"
(PRNDL1 & PRNODL1)

TravisMartin · 10-09-2009, 07:39 AM

Thanks. I really figured the sender to mount there, but can't find the wire that should go to it. But the harness is in pretty bad shape and I'm going to have to redo it anyway; I'll find it. I'm already looking for a '91 up donor to give up the 4L80E harness and ECM. I at least have the good fortune that I don't have to drive the dually regularly so I can work on it without being under pressure to get it back together in a hurry. I'm planning to pull the cab and gut it for a color change and semi-restoration, but I'd like to have the harness sorted out first if I can. This truck spent its life working hard on a ranch and is incredibly filthy, or was...I've been cleaning on it a lot and think maybe I've taken it from "filthy" to maybe just "nasty"...

Enjoyed your cluster thread. Might have to do something similar one day. I'm not a fan of the white gauges (I'm an old fart; I've looked at a lot of black gauges over the years) but otherwise looks great. I think I would have put the brake warning light in the 4WD hole and just left the seat belt light off (I usually know whether they're buckled or not without a light...) I certainly admire your patience and workmanship. And I really, really want me some train horns before I die...

Travis

10-03-2009, 06:43 PM	#1
TravisMartin Curmudgeon of Poor Means Join Date: Jan 2009 Location: Lubbock, Texas Posts: 113	1990 Crew Cab Dually (R3500) I recently got this truck in somewhat poor shape and am trying to bring it back. It's a square body, so I asked essentially the same questions in the 73-87 forum, but got to thinking that mechanically it is the same as a 1990 C3500, so thought I'd ask here too. It's a 454 with TH400; I can't find where the oil pressure sender is supposed to be (has had an aftermarket mechanical gauge installed) and I want to put it back stock. If I knew where the sender is supposed to be I should be able to find the wire. I'd really like to convert it to a 4L80E also. I'd like to do this with factory parts as if it were a 1991 model. I assume the transmission is controlled from the ECM? If so, I should be able to do this with a 1991 ECM and harness, assuming I can find one... Any help will be greatly appreciated. Thanks, Travis

10-03-2009, 09:11 PM	#2
ChevLoRay Old Skool Club Join Date: Jun 2001 Location: Benton, AR "The Heart of Arkansas" Posts: 10,880	Re: 1990 Crew Cab Dually (R3500) Welcome to our Forum! I don't have the answers you seek, but I'll be glad to keep an eye out and help direct you to the right place if this doesn't work out. __________________ Member Nr. 2770 '96 GMC Sportside; 4.3/SLT - Daily driven....constantly needs washed. '69 C-10 SWB; 350/TH400 - in limbo The older I get, the better I was.

10-09-2009, 01:44 AM	#3
BLE 'BURBAN In the Forgotten far North. Join Date: Jul 2007 Location: Anchorage, Alaska Posts: 2,627	Re: 1990 Crew Cab Dually (R3500) The O.P.Sending Unit should be installed just above the oil filter on the drivers side of the block. Converting to an overdrive tranny will require shortening the driveshaft, as well as swapping out the main computer and the harness both under the hood and under the dash with one from a donor vehicle that has what you're after like a suburban, blazer or another crewcab if you can find one. Also you'll want to swap out the *"PRINDLE INDICATOR"* with a *"PRINODLE INDICATOR"* (PRNDL1 & PRNODL1) __________________ 1987 R3500 CREW CAB DUALLY (BIG RED)Acquired 06/12/2015 1990 chevy suburban V2500 5.7L My cluster Mods-Nov 2007 overhead console Stereo install Round 2 Aug 2009 Heated/turn signal mirror upgrade

10-09-2009, 07:39 AM	#4
TravisMartin Curmudgeon of Poor Means Join Date: Jan 2009 Location: Lubbock, Texas Posts: 113	Re: 1990 Crew Cab Dually (R3500) Thanks. I really figured the sender to mount there, but can't find the wire that should go to it. But the harness is in pretty bad shape and I'm going to have to redo it anyway; I'll find it. I'm already looking for a '91 up donor to give up the 4L80E harness and ECM. I at least have the good fortune that I don't have to drive the dually regularly so I can work on it without being under pressure to get it back together in a hurry. I'm planning to pull the cab and gut it for a color change and semi-restoration, but I'd like to have the harness sorted out first if I can. This truck spent its life working hard on a ranch and is incredibly filthy, or was...I've been cleaning on it a lot and think maybe I've taken it from "filthy" to maybe just "nasty"... Enjoyed your cluster thread. Might have to do something similar one day. I'm not a fan of the white gauges (I'm an old fart; I've looked at a lot of black gauges over the years) but otherwise looks great. I think I would have put the brake warning light in the 4WD hole and just left the seat belt light off (I usually know whether they're buckled or not without a light...) I certainly admire your patience and workmanship. And I really, really want me some train horns before I die... Travis



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