Find test current in Thevenin circuit
Both answers seem wrong to me. I didn't check your calculations, but you are complicating matters a lot. If you don't consider your test generator, your circuit is a simple parallel/series combination of resistors: \$R_1\$ is in series with \$R_5\$ (call the result \$R_{15}=R_1+R_5=11k\Omega\$). This latter is in parallel with both \$R_2\$ and \$R_4\$, so your Thèvenin equivalent resistance is:

$$
R_{th}=\dfrac{1}{\dfrac{1}{R_{15}} + \dfrac{1}{R_2} + \dfrac{1}{R_4}}\approx1.3k\Omega
$$