Unfortunately, wrong bolt pattern. The GMT400 3500HD uses 10x7.25" and the hub bore is smaller, and the wheels are hubcentric so it matters. There are 19.5" Alcoa alloys out there in the correct pattern, as optional wheels on RV's that shared the same chassis components as the HD. The HD's themselves only came with the steel 19.5's.
No need to convert the front to 10 lug; the 5 lug pattern is the same bolt circle as the rear 10 lug, just 5 less studs. Uses same wheels front/rear.
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Richard