1975 GMC Sierra Classic Beau James SWB LS swap

Description

1975 GMC C15 Sierra Classic Beau James Edition.As far as I can tell, it is what it was represented to me as and I believe it to be a 100% authentic even though the SPID sticker in the glove box is missing.This Beau was setup from the factory in the rare short bed, big block platform.Block, frame and cab vin numbers all match. This truck was owned by the same gentleman from 1984 to 2016.When I bought the truck a couple years ago I tinkered with it a little bit and then decided I wanted to transform it into something special that was quick, reliable and comfortable to drive.I feel I accomplished that when I was able to take my family of 3 on a 1000+ mile road trip around Texas last year without any issue.This truck is very dependable and I’d drive it anywhere.

First the body was removed, I sent the frame, rear differential and all suspension parts to be sand blasted.When returned all parts were primed with Mastercoat Permanent Rust Sealer/Surfacer and painted with satin black Mastercoat AG111 High Performance Topcoat.Then reassembled with all new Moog steering parts, bushings and AGR performance gearbox.All brake lines were replaced with stainless braided lines along with a rear disc brake conversion from Right stuff. The suspension was set up with DJM 3” lowering spindles and coils trimmed to set ride height.Rear was lowered with a flip kit but the frame was not cut for a notch. The rear also has air shocks to increase load handling if needed.Large 1 3/8” front and rear 1” Beltech sway bars were used keep the truck nice and flat.To clear the large 3” mandrel exhaust 1984+ c10 emergency brake cables were used so the parking brake functions correctly.Eagle Alloy 225 wheels were ordered in a staggered fitment with Nitto Motivo high performance tires.20x8.5 with 235/40/20 on front and 20x10 with 315/35/20 for the rear, Wheels fit perfectly in the wheel wells without rubbing.

There were a few rust spots behind the rear tires on the bedand cab corners (inner and outer) that were cut out and correctly replaced with new sheet metal welded back in. The rust repair areas wereNOT body worked at all, the welds were ground down and spray can paintedover for a temporary fix.Floor pans, rockers and kick panels only had surface rust.Once the patches were welded in, surface rust cleaned up and firewall smoothed to remove unwanted holes.The cab floor, inside firewall, under side of the cab, under side of the bed and exterior firewall were all primed and painted with the same Mastercoat paint system used on the chassis.Cowl seam was also resealed and painted inside.Cab and bed were then reinstalled with new bolts and new rubber bushings.Front and rear chrome bumpers are new and in good shape, the rear has a fold down license plate with a 2” receiver hitch behind it.Front fenders are untouched and will need to be replaced or worked, both have rust in front of and behind front tires.Hood is in good shape, driver’s door is in good shape, passenger door has seam swell in the bottom.I have a correct replacement passenger door shell that will come with the truck.

The drivetrain is where I wanted the most improvement.The speed limit isn’t 55mph anymore so the 454/TH400 wasn’t going to cut it.The running big block was removed and stored (included with sale) because of the matching numbers.After researching I settled in on a LS Gen IV 6.0 iron block out of a 2012 truck with low miles (49K).This motor uses the same head casting as the popular LS3, and has VVT but NOT the problematic DOD.To increase power a Texas Speed VVT 3.2 cam was installed with Texas Speed dual spring kit and titanium retainers. A Straub bronze trunnion bushing kit was also installed to keep things safe.Paired with a LS3 intake manifold, throttle body and cold air intake it is very pleasing to look at.The exhaust flows through 1 3/4” Speed Engineering stainless steel headers, 3” mandrel bent dual exhaust with x-pipe, Dynomax Super turbo mufflers then over the axle to be dumped at the rear bumper.A new baffled fuel tank, sending unit, fuel pump, regulator/filter with braided stainless lines were installed to supply the correct fuel pressure needed to run the fuel injection on the factory ECM& TCM that were data log tuned by Black Bear Performance.The computers are mounted inside the cab and the harness was very neatly reworked to hide as much wiring as possible.The SES light and OBD2 port are easily seen and accessed inside the cab.The transmission is a rebuilt 4l80e with shift kit paired with a FTI billet single disk 9.5” 3600rpm stall converter. A 30k trans cooler has been plumbed in to keep them cool.The converter and cam work very well together, trans shifts good and hard when it is needs to.The factory 12 bolt was fitted with 3.73 gears on a Eaton Posi carrier.No problem spinning both tires but drives nice and stock like around corners without noises or jerking.All the accessories, starter/flywheel, belts, hoses and ect. were bought new or remanufactured to keep problems minimal and for a clean fresh appearance.The engine and trans sits on Dirty dingo mounts with a custom tubular transmission cross member.Dual electric fans on the BBC radiator are controlled by the ECM which keep it cool.One fan is also triggered by the A/C system.

Inside while the carpet was out I installed almost 100 sq. ft. of Fatmat mega mat over the floor, firewall and roof.Another layer of jute mat on the floor and a factory like cardboard backed jute pad on the firewall also help keep things cool and quiet.New carpet and dash pad were installed along with the factor door panels and trim being repainted to freshen them up.The window belt runs and door weather strips were replaced.All the faded wood grain trim was recovered with 3M vinyl woodgrain wrap to refresh the classic look.The seat was recovered to match the factor distinctive Beau James seat style.The original Beau James floor mats are included but one mat has seen better days.It has a few spots getting hard and slightly misshaped and wrinkled, I’ve read about using wintergreen oil to soften the old rubber but I’ve been scared to try.The gauge cluster was replaced with an electronic set from Intellitronix so they would all work with the LS swap. Next the Vintage Air sure fit system was install to keep the cab comfortable no matter the weather.The compressor was mounted low on the passenger side to keep the engine bay looking less cluttered. Battery was relocated under the driver seat mounted to the frame. aPioneer BT,CD,AUX,Radio with 2-6x9’s behind the seat were also installed.The drive by wire Corvette pedal fits the interior styling very well and doesn’t look out of place.To help with braking a dual diaphragm booster was installed with a Tahoe master cylinder, s10 reservoir and CCP disc/disc combo/prop valve.

With all that said I’m sure I’m forgetting some details but I’m trying to represent the truck the best I can so there are no surprises.I’ve personally spent lots of time and money getting this to where it is and working out any little bugs.The next step in my plan was to send it to a paint shop to for bodywork and to get a real paint job. The current paint job was done at Maaco by the previous owner quite a few years ago and the paint has been touched up in several places with spray can paint. Even though the paint isn’t the best it still gets plenty of compliments every time I take it out. It’s crossed my mind to let someone creative try their hand at doing a faux patina look but not sure how it would turn out.There is a fair share of dings to work out butmajor body damage. I’ve stalled and my interest has derailed, hopefully someone comes along and wants to pick up where I left off but if not I’ll keep it with the intention of finishing it one day.Truck for sale as is, where is with no warranty.