flying99,
The 91-92 1/2 ton should bolt right in (I'm almost pretty sure but not exactly). The only difference may be the wiring for the cruise and wipers. An 86 is the same as the 88-91 Subs, Blazers and one tons.
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Gerardo
1983 Custom Truck
TX Plates: "BAD BOW"
http://www.geocities.com/abetterchemist/