I do not have enough information to confirm you statement the basis of the replacement is zero. What was the basis of the old property. What were the mortgages......

There are several worksheets to do a 1031 Exchange. Use one of them to compute the basis. I LOVE a software program called Tax Tools. I automates that particular worksheet AND it does lots of other nifty tax calculations, including a very easy tax planner. If you can fit it into your budget, it is well worth the investment. Excellent company and very good customer support.