From what I remember Mark 1 Tanks supplies a 1/8 Abrams, I know 2 chaps who had them both upgraded to 1/6 Challenger II I think they ran reasonably well this was 6 years ago also around this time 2004-2006 I think it was Kenny Kong who first released 1/8 Challenger II, Leopard 2A5, Chieftain, and Abram’s, Mark 1 Tanks had 1Abram’s to evaluate the model, the gearing was very bad and didn’t allow the tank to turn well on anything other than a flat smooth surface very quickly the gearbox failed so Mark installed one from his own range of tanks, conversations with the manufacture were as usual one sided and wouldn’t resolve any of the issues with the tanks the only conversation they would have was unit numbers that Mark had to buy, this was the only one he had’ I have never seen any others on any forums since then so would guess that only a few exist.

Unfortunately over the years there have been a number of companies Veiro, Metal Box to name just a few who have had great ideas about building large sale tanks 1/8 – ¼ scales all have had major problems with reliability and parts failing or with huge detail faults all have had the same things in common they haven’t listened, wouldn’t improve the shortcoming’s, they have wanted far more than current models built in Europe as in vastly overpriced and worst still have demanded unrealistically large orders with all the defects, hence why none have ever been seen on the net.

Best bet would be to go with Mark 1 Tanks
http://www.mark-1-tank.co.uk/abrams.html