Common substitutes for manned modules(if u dont want to endanger kerbals)

[imcute]

mk1 rocket command pod->1.25 unmanned module+ncs adapter

mk1 radial command pod->mk1 lf tank/ftl 400 tank+1.25 unmanned module

mk1 plane command pod->1.25 unmanned module+ncs adapter+sas module

mk2 command pod->2.5 unmanned module+c7 adapter 1.25

mk2 plane command pod->mk2 unmanned core+mk2 to mk1 adapter

mk2 radial command pod->fuelsage+mk2 probe

mk3 command pod->mk3 to 2.5 adapter+2.5 probe+2.5 to 1.25 adapter

hitchhiker->seq-24 cargo

mk1 passennger module->fuelsage

mk3 passenger module->fuelsage(its almost never wrong to bring additional fuelsage unless ur plane is low on oxidizer and u add a lf fuelsage)