Is the manual transmission used in the w115 diesels plug & play or at least compatible with linkage mod to the later OM616 engines used in the W123? My 1980 240D manual trans has wear on all 3 synchro disks and a drip from the output shaft seal. Still shifts fine with a pause between gears and can be driven this way for a long time. There is a good 4 spd manual available from a W115. Thanks, Don