ponjohn,
I think any 1 ton dually parts from 73-91 should bolt on. I've seen a 87-91 blazer converted to a dually rear!!! It was for sale. If I see it again I'll take a picture of it. If the dually will bolt to a Blazer the rear ends should bolt to a truck. The easiest conversion is to find a dually bed. The fenders are availble but you would have to put them on yourself.
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Gerardo
1983 Custom Truck
TX Plates: "BAD BOW"