Takes some fixturing and precise measurements to shorten the tubes and reweld them correctly, not exactly a job to do on the garage floor!!! When you're done, you will either need new axles or have the axles you have now cut and resplined.....if the axles are large enough diameter when you have them cut to allow resplining.

Many companies, Moser and Currie are the ones I use, will sell you a housing with the correct length axles for any rear end width you specify....