Available four chars domains with results in the WayBack Machine

As always, all of them were available at time of posting:

20CH.NET
70VD.COM
YJDQ.NET
2RAY.NET
DSR1.NET
SWJU.NET
TM43.COM
BFWM.NET
QHAG.NET
G246.COM
SMZJ.NET
SGSQ.NET
KM3H.COM
RVL3.COM
ZTKT.NET
R-PC.NET
NXWX.NET
63TW.COM