I think that you can just use the pumkin or third member and keep the the housing and axles on your 49,if you want to. I know the 62 third member will bolt in and I think the 64 will also. Someone else will probably chime in and tell you for sure. I just changed the third member out on my 1949 and it wasn't hard to do at all. Good luck on your 49. Either way you'll have to get a new drive shaft and be sure and set the pinion angle. Also you'll have to get another trans. or get a another rear open drive part for your transmission. From 1955 through 1962 I know will interchange and I think the 1964 will too. Lot less work plus you get a better ratio. Your's is probably a 4:11 ratio. Steven
