Is it absolutely necessary to lengthen the driveshaft for a 6" lift?

[NW 150]

My F100 still sits a little lower in the front than the rear, even after I installed new 4" lift springs earlier this year. I am considering adding 6" lift springs next year, and I've read stuff about lengthening the driveshafts. Now the rear shaft is fine I've had that through as much abuse offroad as it's going to get at the current height with no issues and it won't be raised anymore out back. I also have a drop pittman arm, and I'd probably add drop radius arm brackets even though the front has been degree'd better for the current lift without the drop brackets.

[77 1/2 F250]

Only if you don't want to drop driveshafts while flexing.

[hasteranger]

No, its not necessary.