In a 1031 if I take out part of the proceeds what happens tax-wise?

[Paul Doherty]

If I sell a property I own completely (worth 175k after realtor's fees) and want to keep 50k of the proceeds and 1031 the rest into 2 or 3 new properties how do the tax consequences play out?  Do I pay 15% on, say, 58k (paying about 8k in taxes) so I end with 50k?  Or is the amount of taxes paid based on how much I actually gained?  I originally bought the house for 89k in 1996.  I didn't know about mandatory depreciation and I've been renting it almost 10 years, so I only started depreciating it on taxes a few years ago.  Would the taxes owed on the 58k (or whatever amount) I keep out from the sale be taxed differently based on the cost basis of the house (what I paid minus what's been depreciated)?  Can someone help me make sense of this?  To summarize:

- Sell house worth 185k, netting 175k.  House was bought for 89k in 1996.

- Keep a net of 50k after whatever taxes are owed.

- Invest the remainder (~117k) into two or three other properties.

Thanks for any help/advice!