No problem, though I did not create any algorithmic equations or anything fancy... just some old-fashioned measuring tape, trial and error with spring compression testing and measuring again and again. I wanted a bit of rake in the back so made the shackles a little longer to give me an extra half an inch in the back.Can I inbox you about how you custom made your shackles?
I just need to know how did you do your math.
If you are maintaining a stock suspension, then the direct replacements (no lift) greaseable shackles are what you want.