Pre-Owned 4D-014-003S Class 29 D6107 BR Blue, Headcode Box (Full Yellow End) Diesel Locomotive DCC SoundPre Owned Item, in as new condition. Test Run. The BR Class 29 is a type of Bo Bo diesel electric locomotive designed for both freight and passenger use. Although outwardly similar to the Class 22, they actually share no mechanical parts and in fact were a modified Class 21 with a replacement Paxman engine with improvements to power output. These modifications were carried out between 1963 and 1965 mainly at the Polmadie Traction & Rolling Stock Depot