Hi Lynn, I spoke before about an axle change. I don't know what your trying to do with your wagon. Are you looking for more speed on the hi-way, or more power to the rear wheels. The 283 is a great engine but you have to do firewall work for the distributor to make sure you can remove the cap at a later time or move the motor forward some and use an electric fan. The old motor mounts will need to be removed and new one welded in. ( available at Novak and Advance adapters) If you do a motor swap remember the motor sits approx. 1" to the drivers side so that the front driveshaft will clear the starter. I installed a Buick motor in mine due to the distributor being in the front so there was no firewall cutting. ( a ford motor also has the distributor in the front) You need to look on the internet about the cost verses MPH of an overdrive. When I looked into it it was around $750.00 and was only going to gain around 8-10 MPH while most speed limits where I live are between 60-70 MPH and that just wasn't going to work. ( I spent $350.00 on both rears in mine truck.) The stock rears (front and back) have a very small ring and pinion gears there for changing them was not an option, so I changed the back rear using a 1978 blazer rear which was 60" from backing plate to backing plate. I had to center it up under the springs and weld new axle tube- spring brackets that I purchased at tractor supply. I installed a 3.73 ring and pinion ( front and rear) and now I cruse at 70-75 MPH The issue with the blazer rear is that it has six lugs, but you should be able to change to a 5 lug axle. My front axle is a D44 from a 1974 scout II which was only 1/2" wider then the stock front axle which made it 1/4" on each side plus it has disc brakes so I upgraded the master cylinder for better stopping power because it now goes faster. I also had to build a new transmission/ transfercase mount. Just remember before spending a lot of money on an overdrive how fast are you looking to go, Your going to loose power at the higher end, you don't have to change both rears at the same time, just leave the front driveshaft off until you change the front rear, you are going to need adapters, axle u-bolts, brake lines, and possible of new drive shafts or old one modified, If you can purchase the restoration guide from Willys America it has a wealth of information on changing motors, rears, axles, parts, identification of the different years, it's a great source of information