Re: 14bolt rear - from a blazer
They never put the 14 bolt in a first or second generation Blazer. If it has hubs sticking out it is a full floating 14 bolt. If not, it is a semi-floating 14 bolt. The 14SF can have both six and eight lugs. It can also have five, but it only came in the 454SS.
If it is an 8 lug 14SF then it isn't worth much in my opinion. It is heavy, still has c-clips, and is still 8 lug. The 14FF is better than an 8 lug 14SF. If it is a 6 lug 14SF then I'd get it.
You can also get a 6 lug 14SF out of a 96up Savanna/Express van.