I've built 20+ trikes in the last 30 odd years. From VW to V-8 to shaft and chain drive. The little 7.5 Ford is good all around. Cheap, strong, parts available. Just remember, it's not just simply turning the rear end over so it runs backward. The gears were not set up to go backwards for any length of time. You MUST (and I mean MUST) set the mesh (lash) of ring and pinion on the back side of gears. First time I thought that little gear whine wasn't much to worry about. IT WAS. I thought I just got a bad rear end and did the same thing AGAIN. Then sought help. Set 'em up right and they will last. Also, when you flip the axle, the pinion bearings that used to be below oil level are now high and dry. So now you need to make a filler plug high enough these bearings run in oil. I just drilled diff cover and welded in a pipe fitting that took a threaded plug. Currently I have an independent rear end from a late T-bird laying around, and I think my 88's 92K mile rear is starting to whine. Yup. That's my story to the Mrs. and I'm sticking to it. Good luck to all you trikers. Free on 3!!