WILL IT FIT!!!!! well i guess it should but what kind should i look for 10 bolt or 9 and is the 9 the same as the one in my truck now. it is a 9 bolt 3.42 posi im thinking of doing the swap to a 3.73 and also changing my th350 to a 200r4 as apposed to a 700r4 well anyway thanks

 

its also an 84 truck

 

You want to put an f-body rear in an s-10? It's way too wide. I know someone who did this and of course the brackets need to be cut off and different ones installed, but it looked terrible.
You definatly don't have a nine bolt if it's the original rear, it's a 7.5 with 26 spline axles. Why not just get an s-10 rear and bolt it right in? My '87 came with a four cylinder and 3.73 gears. I ran 13 flat at 107 with this rear and a v-8 with a 700R4.

 

Maybe someone can post the width of the f-body rear to help you . The s-10 is 55" from wheel flange to wheel flange (wheel mounting surface). if it's 2" to 3" wider you can go with a rim with 5" back spacing like the 16x8 camaro rims.

 

fogot to mention the truck is lower and has 6" blocks in the rear i plan on raising them soon to say 4" or something and i has the gold 16" gta rims painted black