I believe you are better off with 4.6 diff ratios for 35's. It is closer to standard ratio than 4.3 diffs. If you are running 35's it's a fair chance you actually use the thing offroad and 4.6's are much better offroad.
IMO standard ratios are to short. Ie 4.1 with 3.1's
I have 33's with 3.9 and for work purposes only I'm getting 4.1's put in soon.
I have ample power and super low spool up but it's the initial take of I feel I would benefit from a lower cog.
Towing a trailer all day sucks with 33s and 3.9s 4.2tdi. Would easy say 4.3s for 35s would be the go. Im even considering changing mine to 4.3s and run 33s just for take off grunt. Not sure how the top end revs would go though.
Ive got 4.1s on 35s and will upgrade to 4.3s one day. Mine is similiar to Chopped - only spinning at 2100 @ 100km/h which is 90 on my speedo. 2100 is a bit too low for the ht18.... Still pulls okay even when towing but there is a fairly large gap between the 2nd, 3rd and 4th gears.