the 3100 had 6 bolts and was a 16, the 3600 had 8 bolts, 3/4 tons (3600) had 15", the 17" came on the 1 ton or 3800 and these were also 8 lug

1949 Chevy 3600 Flatbed all orginal
1964 gmc 4000
1973 gmc 6000
2005 chevy duramax 4x4
1994 chevy 1500
Trucks are GM and Tractors are Orange

"I don't measure a man's success by how high he climbs but how high he bounces when he hits bottom." - General George S. Patton