8 on 6.5" (165ish mm) til 2009. 2010 is a changeover year so not sure what you'll find. 2011 and newer is definitely 8 on 180mm.
They are metric studs. Scoop up the lug nuts from the front wheels if they're around. I try to put stuff like that inside the vehicle and not bust stuff up so the next guy has a chance of finding the parts if they need them. No need to smash up stuff or drop on the ground things that someone else might need.
Axle ratio RPO codes...
https://www.crawlpedia.com/rpo_axle_codes.htm
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1959 M35A2 LDT465-1D SOLD
1967 Dodge W200 B383, NP420/NP201 SOLD
1969 Dodge Polara 500 B383, A833 SOLD
1972 Ford F250 FE390, NP435/NP205 SOLD
1976 Chevy K20, 6.5L, NV4500/NP208 SOLD
1986 M1008 CUCV SOLD
2000 GMC C2500, TD6.5L, NV4500
2005 Chevy Silverado LS 2500HD 6.0L 4L80E/NP263
2009 Impala SS LS4 V8
RTFM... GM Parts Books, GM Schematics, GM service manuals, and GM training materials...
Please include at least the year and model in your threads. It'll be easier to answer your questions.
And please let us know if and how your repairs were successful.