we both made our own rear shackles.  the rule of thumb for shackle is they lift your truck half of the length you are extending.  So if you wanted two inches of lift you make the shackle 4" longer.  My rear shackles are 3" longer eye to eye than stock.  they are made out of 2x3x8" flat stock and I think brads are the same just maybe 9 or 10" eye to eye.  i don't think you should have problems making your own shackles as long as you use good sized metal, but if you go really long they will change your pinion angle and that may cause some probs.