i popped a TH700 behind mine, kept the 3:36 diff for now... a bit sluggish on take off, but goes well. Am thinking of going to a 3:08, but take off would be even slower, but the speedo is so far out.... 20k diff between speedo reading and actual speed.... gotta b real careful. Need to decide what to do, different diff or get the speedo modified.... can't decide damm it! There's a windowless WB on ebay at the mo.... http://www.ebay.com.au/itm/Holden-Pa...item1e670fbcab. Has small round windows in the back. May have had the windows welded up at some stage, hard to tell from the pics.