I get owners manuals off Ebay. I think people get them from wrecking yards and sell them.
This should help:
2006 CHEVROLET TRUCKS SILVERADO 2500 HD PICKUP 6.0L 8-cyl Engine Code
LUBRICANTS & FLUIDS:
Engine Oil
Grade 1......API*
Signature Series 0W-30 100% Synthetic Motor Oil (SSOQT)
SAE 5W-30 Synthetic Motor Oil (ASLQT)
XL 5W-30 Synthetic Motor Oil (XLFQT)
All TEMPS......5W-30 [1]
Below -20F......0W-30
Manual Transmission,NV4500......GL-4 [2]
Synthetic Manual Transmission and Transaxle Gear Lube (75W-90) API GL-4 (MTGQT)
Manual Transmission,ZF S6-650......SLF [3]
Torque-Drive Synthetic Transmission Fluid (ATD1G)
Automatic Transmission,1000......AF6
Low Viscosity Synthetic ATF (ATLQT)
Automatic Transmission,4L80-E......AF6
Low Viscosity Synthetic ATF (ATLQT)
Standard Differential, Front......GL-5
ALL TEMPS......75W-90 [4]
SEVERE GEAR 75W-90 Synthetic EP Lubricant (SVGQT)
Standard Differential, Rear......GL-5
ALL TEMPS......75W-90 [4]
SEVERE GEAR 75W-90 Synthetic EP Lubricant (SVGQT)
Transfer Case,NVG 261-NP2......GLS [5]
Torque-Drive Synthetic Transmission Fluid (ATD1G)
Synthetic Universal Automatic Transmission Fluid (ATFQT)
Transfer Case,NVG 246-NP8......SLF [6]
No AMSOIL Product Recommendation
Transfer Case,NVG 149-NP3......GLS [6]
Torque-Drive Synthetic Transmission Fluid (ATD1G)
Synthetic Universal Automatic Transmission Fluid (ATFQT)
Transfer Case,NVG 263-NP1......GLS [6]
Torque-Drive Synthetic Transmission Fluid (ATD1G)
Synthetic Universal Automatic Transmission Fluid (ATFQT)
Fluids
Power Steering Fluid......PS
Power Steering Fluid (PSFCN)
Brake Fluid......HB
AMSOIL Brake Fluid DOT-3 (BF3SN)
Clutch Fluid......HB
AMSOIL Brake Fluid DOT-3 (BF3SN)
[1] SAE 5W-30 is preferred.
[2] Synthetic gear oil, GM part no. 12346190 or equivalent.
[3] GM part no. 12378515 or equivalent
[4] Synthetic lubricant, GM part no. 12378261,
or equivalent product formulated to meet
GM specification 9986115.
[5] GM recommends Part No. 88861800 (Canada 88861801)
or equivalent for manual transmission, transfer
case applications.
[6] GM part no. 12378508 (U.S.), 10953626 (CAN)
FILTERS:
Oil Filter Absolute Efficiency Oil Filter (EAO32)
Oil Filter WIX 51042 Oil Filter
Air Filter Absolute Efficiency Air Filter (EAA123) [1]
Air Filter Absolute Efficiency Air Filter (EAA123) [2]
Air Filter INJEN-AMSOIL Air Intake System (PF7050P)
Air Filter WIX 42488 Air Filter [1]
Air Filter WIX 42487 Air Filter [2]
Transmission Filter WIX 58904 Trans Filter [3]
Transmission Filter WIX 58847 Auto Tran Filter [4]
Transmission Filter WIX 58608 Auto Tran Filter [5]
[1] Heavy Duty Version
[2] Light Duty Version
[3] 4L60E - Shallow Pan
[4] 4L60E - Deep Pan
[5] 4L80E - Pan Gasket Reusable - Not Included
NGK PLUGS AND WIRESETS:
GPSERIES PLUG TR5GP
IXIRIDIUM PLUG TR5IX NGK7397
PREMIUMIRIDIUM PLUG ITR5F13 ^
PREMIUMPLATINUM PLUG PTR5D-10 *
VPOWER PLUG TR5 NGK2238
WIRESET WIRESET RC-GMX102 NGK51430 [1]
[1] "Use w/Coils Stamped 19005218 (9.2"" Leads)"
WIPER BLADES:
Blade Class Driver Passenger
ExactFit T221 T221
NeoForm T16220 T16220
Winter T37225 T37225
CHASSIS LUBRICATION:
2WD
6 Fittings, 0 Plugs..........LB
Series 2000 Synthetic Racing Grease NLGI#2 GC/LB (GRGCR)
Synthetic Heavy-Duty Grease NLGI #2 GC/LB (GHDCR)
Synthetic Multi-Purpose Grease NLGI #2 GC/LB (GLCTB)
4WD
11 Fittings, 0 Plugs..........LB
Series 2000 Synthetic Racing Grease NLGI#2 GC/LB (GRGCR)
Synthetic Heavy-Duty Grease NLGI #2 GC/LB (GHDCR)
Synthetic Multi-Purpose Grease NLGI #2 GC/LB (GLCTB)
CAPACITIES:
Engine, with filter..........6.1 quarts [1]
Cooling System, With AT Electric Fan Initial Fill..........16.7 quarts
AMSOIL Antifreeze and Engine Coolant
Cooling System, With AT Engine Fan Initial Fill..........16.2 quarts
AMSOIL Antifreeze and Engine Coolant
Cooling System, With MT Engine Fan Initial Fill..........16.7 quarts
AMSOIL Antifreeze and Engine Coolant
Automatic Transmission, 1000 Initial Fill..........7.4 quarts [2]
Automatic Transmission, 4L80-E Initial Fill..........7.8 quarts
Automatic Transmission, Total Fill
4 speed 4L80-E..........13.6 quarts
6 speed 1000..........12.7 quarts
Manual Transmission, NV4500 (TOPC)..........8.1 pints
Manual Transmission, ZF S6-650..........12.7 pints
Differential, With 8.25 RingGear Front..........3 pints
Differential, With 9.25 RingGear Front..........3.6 pints
Differential, With 10.50 RingGear Rear..........5.5 pints
Differential, With 11.50 RingGear Rear..........6.4 pints
Differential, With 8.6 RingGear Rear..........4.3 pints
Differential, With 9.50 RingGear Rear..........5.5 pints
Differential, With 9.75 RingGear Rear..........6 pints
Transfer Case, NVG 149-NP3..........4.5 pints
Transfer Case, NVG 246-NP8..........4.1 pints
Transfer Case, NVG 261-NP2..........4.1 pints
Transfer Case, NVG 263-NP1..........4.1 pints
[1] After refill check oil level.
[2] DO NOT drain the fluid if only the transmission spin-on oil
filter is being replaced.
TORQUES:
Oil Drain Plug.....18 ft/lbs
Manual Transmission NV4500
Fill Plug 27 ft/lbs
Drain Plug 27 ft/lbs
Manual Transmission ZF S6-650
Fill Plug 26 ft/lbs
Drain Plug 26 ft/lbs
Transfer Case NVG263-NP1
Fill Plug 15 ft/lbs
Drain Plug 15 ft/lbs
Transfer Case NVG261-NP2
Fill Plug 15 ft/lbs
Drain Plug 15 ft/lbs
Transfer Case NVG246-NP8
Fill Plug 15 ft/lbs
Drain Plug 15 ft/lbs
Transfer Case NVG149-NP3
Fill Plug 15 ft/lbs
Drain Plug 15 ft/lbs