If you sell stock that is eligible for Long Term Capital Gains and you are married with income below 73K is the cap. Gains 0%? Do you need to send in estimated taxes on the would be LTCG's? Then list the estimated tax on your return and recoup it later?

You must be in the 10 or 15% tax bracket to have no LTCG. Based on your info, it would appear no. I would just do the 1040 at tax time and see where you fall.

Like MA641 says, you will pay some LTCG tax.

As for the need to pay estimated tax, that depends on whether you will end up owing any tax when you file. It is likely the taxes withheld from your salary may be enough to cover any tax liability.

No Salary, living on SS and my IRA. Have some non IRA money invested. In the past, I have been below the 73K. 2013 I will be getting money back, filed for an extension due to wife passing away and a problem with Turbo Tax. 2014 I will be able to file joint but will have to file Single in 2015.

Then make estimated tax payments when the stock is sold based on a 15% tax rate.

Is the 73K adjusted Gross Income or is it unadjusted?