Hi Alain,
You can use iRules to check and modify header information for this. Check out the link below (written by Nathan):
https://devcentral.f5.com/questions/need-an-iso8583-application-switch-for-card-transactions
https://devcentral.f5.com/Community/GroupDetails/tabid/1082223/asg/71/afv/topic/aft/1172446/aff/2297/showtab/groupforums/Default.aspx
Another is from my own problem before, its also a customized 8583 and similar to the first link above. I'm not really good at irules myself, but you can check out the comments, there are other links in there that may be useful. Hope this helps and good luck!
https://devcentral.f5.com/questions/check-for-string-in-tcp-payload-from-a-specific-position
Lez