Mr Cox thanks for the help. Was searching web and found a suppler for balloon tanks. Also found thread in 1/2a forums on this subject.
specs. Balloon Tank for 1/2A Capacity 1-3/4 oz $5.95
http://www.rsmdistribution.com/index-2.htm
What do you think about this. Will be using pull pull system on Rudders.
Thanks again.