How expensive is it and is this something acheieveable for an amature car enthusiast??

 

disc brake conversion..
it's been discussed, use the search feature

 

It may be easier to do the conversion by changing the entire rear axle. Thats what I did and it was way easy, would even be pretty easy for a novice. What year blazer do you have?

 

pull axle shafts out, unbolt backing plate/mounts. mount on disc brake stuff, slide axle shafts back in.
easier then swapping rear axles, then you can change your fluid while your at it. as well as bearings and seals
different proportioning valve and possible master with disc brakes though.

 

http://www.ssbrakes.com/commerce/det....cfm?nPID=8271
that should help you out