We can make and export trailer parts in China. Pls have a look at the technical information for some products as below : 
1. trailer couplers:7000lbs,12500lbs ,etc.capacity are available, ball size 2-5/16",designed for 50 degree A-frame tongue,painted finish. 
2.  Trailer straight coupler: Size : 2",2-1/2", Capacity 3500lbs, 
1-7/8,2-1/2",Capacity:2000lbs,etc. 
Color:Chrome or painted finish or oil finish,Type:US type, 
3.  Trailer coupler: Size:50mm,2-1/2",3500lbs,Color: Chrome or power coating ,Type: EU type,Steel board thickness:3mm,2.5mm 
4.    Hitch ball: ball size: 1-7/8",2",2-5/16", etc. Color : Chrome, 
surface treating passed CASS TEST,Salt Spray Test 22hrs, No red rust,V-5, Type : US type 
5.     Ball mount : with one & two & three balls :ball's size can be choosed,color: power coating and chrome, 
6.  wheel hubs:The materials are ductile cast irons or steels. Galvanized Hubs, 4-5 studs. PCD 4" or 4.5" .Bearing type is roller. Axle capacity 750kgs,1000kgs,1500kgs,etc.Surface treatment: spray-painting or zinc-plated. 
7 . hitch balls :Ball Dia.1-7/8",2",2-5/16",Shank Dia.3/4",1",1-1/4",Shank Length 1-3/4",2-1/2",2-1/8",2-1/4",2-1/8",2-3/4",etc. are available. 

8. square jack :Capacity 2000kgs,5000kgs,8000kgs,etc.net weight : 16kgs,32kgs,etc.Max. Height : 1540mm,1240mm,etc. style : plate ,etc. which are available. 
9. brake drums:Materials:grey cast iron, Surface treatment: zinc-plated or spray-painting . Brake Dia.:160mm,250mm,203mm,200mm,250mm,Shoes width : 35mm,40mm,50mm,Number of Studs : 4 or 5,Stud Size : 7/16",3/8",M12,M14,5/8",PCD :101.6mm,165.1mm,152.4mm,139.7mm,165.1mm,Brake Type: Knott.