Same box but different bell housing and input shaft. That picture was taken a long time before Harvey was on the road, hence the cleanliness :I, and before I swapped the bell housing and input shaft from a Commer box. Trouble is the gear wheel on the input shafts are different - I found that out later after it shed it's teeth So best going for an earlier, non-Arrows series one, as it goes straight on as used on Rapiers, Sceptres and Alpines
But you still need to shorten the prop. Also be aware that some boxes had coarse splines on the input and output shaft and some had fine splines - some had a combination of both. Just make sure you have the right prop to fit the splines on the output shaft, it's just a matter of using a different clutch plate if the input end is different to what you already have.