My truck is a '91 Ext. Cab 4x4 F250 w/ the ZF5spd. w/ the front end Converted to ALL F350 parts,(D60, track bar, stabilizer bar and springs).At what point do I need to worry about lengthening the driveshafts? I assume the front will be at around 6"s, but w/ the rear being 100 yards long, w/ a center bearing, can I go 8" or so before worring about it?

I'm thinking a 4" Fr. spring w/ a front shackle reversal, so I can take out the track bar and get ~3" more lift, then lifting the rear to match.

Also, will the generic aftermarket drop pitman arm work w/ this much lift? I've only ever seen the one listed, not 2 for different lift heights.

Thanks,
Mike