These designs represented the final development of the 70′ coach and marked the beginning of the bow-ended era. The bow end reduced the length of the corridor bellows and required the introduction of buckeye couplings and fold-down buffers. D90 carriages had a bowed passenger end and flat brake end; the otherwise identical D83 (kit W4AK) was flat at both ends for compatibility with existing stock. The right-handed versions were D82 and D84 respectively (kits W3K and W3AK).
The photos show the right hand van version to diagram D84.