So, I’ve been looking all over the internet for an answer, called multiple techs at Chevy, but no one has an answer. I have a 2004 Chevy Silverado 2wd, 1500 base LS model pickup. The catch is it has torsion bars. I used a vin decoder to find out all this information. I was looking to get a suspension upgrade and need help understanding how the upper control arms are different and what ones will work. Most shops are stubborn and won’t help me figure out the issue unless I pay a pretty penny, to find out what product fits.
The decoder also stated only 792 Manufacture ID.
Here are is the build info;


AIR CLEANER HIGH CAPACITY; ARM TORS BAR SPRING ADJ (G); ARM TORS BAR SPRING ADJ (H); NOISE LEVEL CONTROL; BODY EQUIPMENT,FLEETSIDE PICKUP BOX; BUMPER,REAR STEP,INCLUDES IMPACT STRIP(CHROME); STRIP,FRONT BUMPER IMPACT; BRAKE VAC POWER,DISC/DISC,7,200 LBS; MOLDING B/S EXTERIOR, BRIGHT; COLOR COMBINATION SOLID; CRUISE CONTROL,AUTOMATIC,ELECTRONIC; EXTERIOR COLOR,PRIMARY,INDIGO MET; CHASSIS HIGH PERFORMANCE PACKAGE; SILVERADO/SIERRA CLASSIC/SLE PACKAGE; CONSOLE ROOF INTERIOR,CUSTOM,COMPASS & OUTSIDE TEMP; DEFOGGER,REAR WINDOW,ELECTRIC; COOLING SYSTEM,TRANSMISSION,HEAVY DUTY; EMISSION SYSTEM CALIFORNIA LEV II PLUS; CALIFORNIA EMISSION CERTIFICATION; PACKAGE OPTION-; CONTROL SALES ITEM NO. 127; CONTROL SALES ITEM NO. 137; CONTROL SALES ITEM NO. 9; CONTROL - SALES ITEM NO. 100; CARPET,FLOOR AND WHEELHOUSE; COVERING,FLOOR MATS,FRONT AUXILIARY; COVERING,FLOOR MATS,REAR AUXILIARY; COMPONENT FRT LH COMPUTER SEL SUSP (6YT); COMPONENT FRT RH COMPUTER SEL SUSP (7YT); TIRE FRONT P275/55R20-111S BW TL ST AL2; GENERATOR,105 AMPERE; GLASS,DEEP TINT(REAR SIDE WINDOWS AND REAR DOOR WINDOW); GRILLE RADIATOR, BODY COLOR, W/CHROME EMBLEM; GVW RATING 6200 LBS; THROTTLE CONTROL VARIABLE SPEED (ELECTRONIC); AIR CONDITIONER,FRONT,MANUAL TEMPERATURE CONTROL,AUXILIARY TEMPERATURE CONTROL; LOCK CONTROL,REMOTE ENTRY(KEYLESS ENTRY SYSTEM); LOCK,SIDE DOOR,ELECTRIC; FRT END SUBASSEMBLY INSTALLED (MODULAR OPTIMIZATION; LAMP,FRONT FOG; MARKET BRAND CHEVROLET; MIRROR,OUTSIDE,RH AND LH REMOTE CONTROL,ELECTRIC,DEFOG; AXLE,REAR,POSITRACTION,LIMITED SLIP; PLANT CODE OSHAWA, ONT, TRUCK, GM OF CANADA; WINDOW,ELECTRIC OPERATED,SIDEWINDOW,POWER OPERATED,ALL DOORS; AXLE,REAR,3.73 RATIO; AXLE FRONT (BASE EQUIP) FOR SCHEDULING GVW PLATE; RADIO AM/FM STEREO, SEEK/SCAN. AUTO REV MUSIC SEARCH CASS, CD, AUTO TONE, DATA SYSTEM, CLOCK, ETR; SPRING,REAR(BASE EQUIPMENT); SEAT,REAR FOLDING; TIRE REAR P275/55R20-111S BW TL ST AL2; MIRROR,INSIDE,REARVIEW,LT SENSITIVE,COMPASS,O/S TEMP DISPLAY; PACKAGE,SPRING SPECIAL; SALES PROCESSING-STOCK ORDERS; PACKAGE-OPTION 02; SPEAKER SYSTEM,PERFORMANCE ENHANCED AUDIO; TIRE SPARE P265/75R16 BW R/PE ST TL AT 114S; SEAT,FRT SPLIT,EASY ENTRY,DRIVER,PASSENGER; CONTROL STEERING WHEEL,ACCESSORY; STEERING WHEEL,LEATHER WRAPPED; TIRE BRAND ALL-; TIRE ALL P275/55R20-111S BW TL ST AL2; HOOK,FRONT TOW; TRAILERING PACKAGE(SPECIAL)(REESE TYPE HITCH); TRAILER HITCH(WEIGHT DISTRIBUTING PLATFORM); TRIM COMBINATION CLOTH,VERY DARK PEWTER; INTERIOR TRIM COLOR,MEDIUM BEIGE/VERY DARK PEWTERINTERIOR TRIM COLOR,VERY DARK PEWTER; TEST DVT, EVAP EMISSION REQUIREMENT; TEST EMISSION, CALIFORNIA ASSEMBLY LINE; VEHICLE STATEMENT - US/CANADA; LABEL,NOTICE TO BUYER; LABEL COMPLETE VEHICLE; SENSOR INDICATOR INFLATABLE RESTRAINT, FRT PASS/CHILD PRESENCE DETECTOR; WHEEL 20 X 8.5, ALUMINUM CAST, CHROMED, 5 SPOKES

 

why would the uppers be different when the tbar goes into the lower control arm? does the dealer parts dept. list different parts for uca between the two designs. rock auto doesn't.