North Korea are proving to be more helpful than expected and have tons of old Soviet era hardware that they would be willing to sell in exchange for some more rocket tech or nuke stuff.
According to Wikipedia the Soviet era tanks NK has is a few thousand T-55s and some T-62Ms. The T-62 varients are likely good enough to use on the battlefield, but the T-55s may not even be worth the fuel it takes to transport them. Remember Russia was fielding some T-55s not by using them as tanks, but by filling them with explosives and sending them uncrewed against Ukainian lines as bombs-with-tracks.
NK also has a bunch of 60 and 70s era Chinese tanks, but China may object to actual Chinese military hardware fighting in Ukraine.
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