Remind your Mom that the IRS will need to know about the Captial Gains income from the sale of the Thompson. At 40%, I believe? And tell her that if she forgets, you'll be sure and remind them on her behalf... After she's filed... And subject to penalities. And interest.
That might encourage her to "trade" it to you on a Form 5.
Capital Gains is 15% there chipper, But i see where your going with it.