How is anyone able to e-file a 2019 tax return with a Form 6252 (installment sale) when the original sale was from 1999?  The taxpayer no longer has their 1999 tax return, and it's impossible to request a copy, or transcript, from the IRS on a return that old.  I just don't have the information to fill out Part 1 of the Form 6252.  How is anyone else working around this?