These files are an entry to this contest;
https://community.ultimaker.com/topic/23246-architect-design-contest-vehicles/?tab=comments#comment-211645
if you look at the file names, the truck types are;
FLT -2T ; 2 ton : electro forklift
FLT-4T-gas ; 4Ton Gas powered forklift
FLT_10T ; 10Ton diesel forklift
NAT ; narrow aisle truck (man up)
RT ; 1.6 ton Reachtruck
OPT: orderpicktruck with 3 rolcages
Tow ; Towtruck