I'm pretty sure the Commando has the same frame width as a CJ in the front. Search for a CJ spring outboard kit, and there are a couple out there. Last one I saw also did a shackle reverse. Even if it's not identical, it's a good start to adapt. Here's a quick one I found: http://shop.poisonspyder.com/Jeep-CJ-Axle-Conversion-Kit-s/83.htm
The short input on a T-18 is fairly easy, but there's no way to put a Dana 300 on the back without an adapter (unless you have a 1980 Scout 300). A Jeep 300 has a round bolt pattern and a splined input that wont match up with the T-18 output. Adding the adapter also means swapping the output shaft on the T-18. If you're looking for lower gearing, for the same money as a 300 adapter, you can do the Tera-Low 3.15 kit in the Model 20 t-case.
Interested in a Scout 300? I have a good one in the shed with a T-18 bullgear. I'd let it go for $650 + shipping, which is less than I paid for it. Bought it as a spare because I had one in my CJ. Sold the CJ about 6 months ago.
Bob
tufcj
