the jumbo and the 955 etc screens jumbo runs a bigger screen in diathan the standard,not sure on width the 860 basically has what u are planning runs 2 standard screens we can o_load it even with the 860 ,mine has had a different hydro motor on it and does a max of 8.5km, when i look back u can tell by watching the flow get slower, mine wasnt a MF accesory had been put on thing will be coming off due to structural problems which is my next comment heres a thought rather than put another chook shed ontop of the big chook shed put a bigger screening unit on the mobile one i have a old inland sales unit here, only had indent cyl,s on it part of the plan is to mount 4 screens on it was going to use the sceeens off the 860 and another set i can access FIl built his own screener screens are 1m dia and 1800mm wide runs 6 of these can put thru about 40tn _hr i used it one yr to grade arrino , took it from 23% down to 4%