Rear axle 1970 c-20 swap with?

[bsgmcc20]

I realize i am not doing what i should. Its late and i was hoping for a pointer maybe.

I am thinking about swaping my L.S 3/4 ton rear axle with 16.5 rims for a posi 3/4 ton with 16 inch rims? I got a quote of $600. from a local Truck dismantler. He was saying that is for a single rim posi out of a 3/4 ton 1980 chevy 8 bolt.

Reason for this option of mine is i have to drive up a 1 mile dirt road and a peg leg does not help me with a load going up. I am having issues with dry ground and not wanting to go 4x4 ing right now. just want both tires to get me up the hill.

In the Morning i will search the site for any info to help me with this indevor.

thanks and im sorry i know it has been posted already i bet