the d35 will swap in there just fine, but the driver side drop brake has the potential to puncture a hole in the d35 diff if you were to hit a bump suddenly. tuff country uses a 3/8" thick plate that you fasten the factory pivot bracket to, instead of giving you a new bracket. (one of the reasons it's so cheap) on a side note, you'll most likely have to shorten the front driveshaft when put the d35 as well.
you will need the extended brake lines, but i think the tuff country lift comes with them. there's an alternative in the tech library that can save you some $$$.