1988 RCSSB "modernization"

kris72079

New member
Nov 17, 2016
5
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0
Bangor, Maine
#1
Ok, so to start I've got a 1988 C1500 RCSSB. It is a base model 5.0/automatic truck. BORING! So, where I'm going with it is a bit more on the entertaining side. Starting with the interior, I am replacing the 1988 - no power options - interior with a full power 1998 (done the right way). After that I will be tackling the underhood area. The upgrades there will include a LQ4/6.0L backed by a 4L80E transmission. The LQ4 will be fitted with turbo (~S475-S480ish) targeting a relatively conservative 650whp. The plan is to park it all on a 5/7 static drop and a custom rear coil over suspension that I can take to the track. Progress will be fairly slow right now as I'm trying to wrap up my LTx 396/4L80E build that almost cracked the 500whp mark N/A (496whp/437tq), but will progress, none-the-less.
 

kris72079

New member
Nov 17, 2016
5
0
0
Bangor, Maine
#2
Re: 1988 RCSSB "modernization"

So I've got started on the interior swap. I did a little research before getting started and like with most other cases, what I realized is that I disagreed with the way some others were carrying out their swaps. Most of what I saw that I didn't like was people retaining the original 88-94 round steering column instead of using the 95-98 rectangular column. The reason behind this is simple, the newer column does not simply bolt-in and replace the original. The column mount that is welded to the firewall is different and so for that matter is the column itself. However, the solution is just as simple as recognizing the problem. I drilled out 8 spot welds and removed 4 nuts to remove the column mount from the truck, then repeated the same process in the donor. The mounts, although physically different, install just the same. Now with the mount re-welded back in the cab, I can properly change the column as well. The steering shaft is different too so that had to be sourced from the donor truck. Like the mount though, although different it installs the same.
 

kris72079

New member
Nov 17, 2016
5
0
0
Bangor, Maine
#3
Re: 1988 RCSSB "modernization"

While the HVAC box of my 1988 is the same as the box from the 1998 donor truck, the controls are different. The '88 controls were all cable driven (mechanical) and the cab used two exterior vents from the wiper cowl area for fresh air into the cab. In the '98 donor truck the controls for blend door, etc are all servo motor driven (electronic) and the drivers side air vent is no longer there. I decided since both interiors were already stripped I'd just remove the entire HVAC box from the firewall for the swap. Simple enough task. My '88 is a no options truck so I removed the A/C evaporator coil from donor box before installing it. By swapping the entire box, I eliminated the need to swap over and doors/diverters as the actuator knobs differ between the manual vs electronic operated controls. I did not look closely, but it did appear that the servo motors might attach to the HVAC original box if needed, therefore a servo/wiring harness swap may be possible with the original HVAC box if desired. As with the column mount, there are slight differences here as well, but most importantly the mounting is exactly the same. As far as the exterior vent is concerned on the drivers wiper cowl area, the donor trucks cowl was still cut for the vent but a blanking plate was installed. Simply remove the plate and transfer to the older style and problem solved. Otherwise you can reinstall the fresh air vent and permanently disable the door (in the closed position obviously) and remove the actuator cable.
 
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kris72079

New member
Nov 17, 2016
5
0
0
Bangor, Maine
#4
Re: 1988 RCSSB "modernization"

As for the interior cabin wiring, again it is different between the 1988 and the 1998 but once again, the important part is that it exits the cabin in the same manner. On the driver side, both C100 connectors are physically the same-as are the Pass Through (P101) connectors on the passenger side. Super easy! Be advised, the wiring itself may differ between truck to truck but the methods of getting from point A to B are the same. For me, this is all that matters as I am doing a Gen IV swap (LQ4, 6.0l) so I'll have to go wire-by-wire when I get to that phase to get everything routed where it needs to be. More on that in the future.
 
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