Karrar is DIO project(defense ministry or better say government) and it will be delivered to Artesh and IRGC,in fact first examples after it is was unveiled were given to Army. Zulfiqar was projet of Artesh,or to be precise it is developed by the Research and Self-Sufficiency Jihad Organization of the Iranian Army, They build many stuff up to prottype,from own founds they have and latter some got in production some not,most of their projects are actually upgrades. As mentioned,FCS and everything else Karrar have,you can install on ulfiqar...that is not issue..and every parade on April 18 (army day) I see more Zulfiqar 3...first was one..than 2....last parade there was 5 without FCS installed and one fully equiped..so they work still some low level stuff...Problem with Zulfiqar 3...it is almost same as Abrams...in size...unlike all other Iranian MBTs whih belongs in to lass of medium MBTs....with 5 and 6 wheels,Zulfiqar 3 has 7 wheels...it is significantly heavier and larger. Zulfiqar 1 was based on M-60...at least hull,with 6 wheels..but Z3 is much larger,Abrams size...now Z-3 use same gun as Karrar and t-72, and probably now would use same FCS...than there is no sense introduce new hull,new heavy MBT and everything else when for sake of production and maintaince it has more sense to go for Karrar..as I said,Z3 use same gun,auto loader,ammunition as Karrar...so why then look like it.and dont forget,it was after IRGC and Hezbollah saw T-90 adventage in Syria Iran decided,first to buy T-90 than latter to go with domestic Karrar..when it was 2013-2014...correct me if I miss year...Zulfiqar started in 1993..