To get custom placed default buildings in your mission open the editor, put a player on the map, than add an object to the map (name it objectx) and save your mission.
Now "Alt-Tab" out of the game (if you arent running Arma windowed) and open your mission file which can be found in

X:\Documents and Settings\Username\My documents\ArmA\missions

Search the mission file for your placed object (objectx) and look for the following line :

vehicle="xxxxxxxxx";

Change the xxxxxx into one of the following :

Land_majak_podesta
Land_molo_beton
Land_molo_drevo
Land_molo_drevo_bs
Land_molo_drevo_end
Land_molo_drevo_krychle
Land_molo_drevo_krychle2
Land_molo_krychle
Land_molo_krychle2
Land_zastavka_jih
Land_zastavka_sever
Land_pletivo_dira
Land_plot_zed_drevo1_branka
Land_plot_istan1b_hole
Land_plot_istan1_rovny_gate
Land_Plot_Ohrada_Pruchozi
Land_plot_zboreny
Land_stanek_1
Land_stanek_1B
Land_stanek_1C
Land_zed_dira
Land_zed_dira_civil
Land_zed_dira_desert
Land_afbarabizna
Land_afdum_mesto2
Land_afdum_mesto2L
Land_afdum_mesto3
Land_afhospoda_mesto
Land_bouda1
Land_bouda3
Land_brana02
Land_brana02nodoor
Land_budova1
Land_budova2
Land_budova3
Land_budova4
Land_budova5
Land_cihlovej_dum
Land_cihlovej_dum_in
Land_cihlovej_dum_mini
Land_deutshe
Land_deutshe_mini
Land_domek_rosa
Land_dulni_bs
Land_dum_istan2
Land_dum_istan2b
Land_dum_istan2_01
Land_dum_istan2_02
Land_dum_istan2_03
Land_dum_istan2_03a
Land_dum_istan2_04a
Land_dum_istan3
Land_dum_istan3_hromada
Land_dum_istan3_hromada2
Land_dum_istan3_pumpa
Land_dum_istan4
Land_dum_istan4_big
Land_dum_istan4_big_inverse
Land_dum_istan4_detaily1
Land_dum_istan4_inverse
Land_dum_m2
Land_dum_mesto
Land_dum_mesto_in
Land_dum_mesto2l
Land_dum_mesto3
Land_dum_mesto3_istan
Land_dum_olezlina
Land_dum_olez_istan1
Land_dum_olez_istan2
Land_dum_olez_istan2_maly
Land_dum_olez_istan2_maly2
Land_dum_patr_nizky_prujezd
Land_dum_zboreny
Land_dum_zboreny_total
Land_dum01
Land_dum02
Land_dumruina
Land_dumruina_mini
Land_garaz
Land_garaz_mala
Land_hangar_2
Land_hospital
Land_hospoda_mesto
Land_house_y
Land_hut_old02
Land_kasarna_rohova
Land_kasarna_brana
Land_kasarna
Land_kasarna_prujezd
Land_kostel_trosky
Land_kostelik
Land_kulna
Land_jizak_test
Land_OrlHot
Land_podesta_1_cube
Land_repair_center
Land_ryb_domek
Land_skola
Land_SS_hangar
Land_SS_hangarD
Land_stanice
Land_statek_brana
Land_statek_brana_open
Land_psi_bouda
Land_statek_hl_bud
Land_Statek_kulna
Land_stodola_old
Land_stodola_old_open
Land_stodola_open
Land_strazni_vez
Land_ZalChata
Land_army_hut_storrage
Land_army_hut_int
Land_army_hut2
Land_army_hut2_int
Land_army_hut3_long
Land_army_hut3_long_int
Land_hut01
Land_hut02
Land_hut03
Land_hut04
Land_hut06
Land_sara_domek01
Land_sara_domek02
Land_sara_domek03
Land_sara_domek04
Land_sara_domek05
Land_sara_domek_hospoda
Land_sara_domek_kovarna
Land_sara_domek_sedy_bez
Land_sara_domek_podhradi_1
Land_sara_domek_rosa
Land_sara_domek_ruina
Land_sara_domek_vilka
Land_sara_domek_zluty_bez
Land_sara_dum_patr_nizky_prujezd
Land_sara_dum_podloubi03klaster
Land_sara_dum_podloubi03rovny
Land_sara_hasic_zbroj
Land_sara_stodola
Land_sara_stodola2
Land_sara_stodola3
Land_sara_zluty_statek
Land_townhall
Land_ruiny_3_dvere
Land_ruiny_3_prasklina
Land_ruiny_3_roh
Land_ruiny_3_stenazbor
Land_ruiny_3_stena
Land_ruiny_obvod_3
Land_pumpa
Land_helfenburk
Land_bouda2_vnitrek
Land_bouda_plech
Land_aut_zast
Land_budova4_in
Land_garaz_bez_tanku
Land_garaz_s_tankem
Land_hruzdum
Land_dum_rasovna
Land_ammostore2
Land_hlaska
Land_vez
Land_brana_krat_1_7
Land_Panelak
Land_letistni_hala
Land_KBud
Land_Nasypka
Land_Tovarna1
Land_Tovarna2
Land_Hlidac_budka
Land_Domek_sedy
Land_posed
Land_leseni4x
Land_leseni2x
Land_domek_zluty
Land_Vysilac_FM
Land_watertower1
Land_telek1
Land_zluty_statek_in
Land_domek_radnice
Land_Panelak2
Land_Panelak3
Land_Hotel
Land_dum_mesto2
Land_nabrezi
Land_nabrezi_najezd
Land_trafostanica_velka
Land_trafostanica_mala
Land_komin
Land_invisible_house
Land_hotel_riviera1
Land_hotel_riviera2
Land_trafostanica_velka_draty

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