Injunan 645 sun shiga samarwa a cikin 1965. Yayin da jerin 567 ya kai iyakarsa a haɓaka ƙarfin dawakai, ana buƙatar ƙaura mai girma; an cim ma wannan ta hanyar ƙara ƙuri'a daga 8+1⁄2 a (216 mm) akan jerin 567 zuwa 9+1⁄16 a (230 mm) akan jerin 645, yayin da yake riƙe da bugun jini iri ɗaya da tsayin bene. Yayin da crankcase aka gyara daga 567 jerin, 567C da kuma daga baya injuna (ko 567 injuna waɗanda aka gyara zuwa 567C bayani dalla-dalla, wani lokacin ake magana a kai a matsayin 567AC ko 567BC injuna) na iya karɓar 645 jerin sabis sassa, kamar ikon taro. Sabanin haka, injin 567E yana amfani da 645E jerin toshe tare da 567 jerin ikon majalisai.

Duk injunan 645 suna amfani da ko dai Tushen abin hurawa ko turbocharger don ɓata silinda. Don injunan turbocharged, injin turbocharger yana tuƙi ne kuma yana da kamanni mai wuce gona da iri wanda ke ba shi damar yin aiki azaman mai busa centrifugal a ƙananan saurin injin (lokacin da kwararar iskar gas da zafin jiki kaɗai ba su isa su fitar da injin injin ba) da kuma turbocharger ɗin da ke tukawa zalla. a mafi girma gudu. Turbocharger na iya komawa yin aiki azaman babban caja yayin buƙatun haɓaka ƙarfin fitarwar injin. Yayin da ya fi tsada don kulawa fiye da masu busa Tushen, EMD ya yi iƙirarin cewa wannan ƙirar tana ba da damar "mahimmanci" rage yawan amfani da man fetur da hayaki, inganta aikin tsayin daka, har ma da karuwar kashi 50 cikin ɗari a matsakaicin ƙimar dawakai akan injunan Tushen don iri ɗaya. motsin injin.