thanks for the info. i thought that 1989 was the crossover year for the 2 wire sensor. couldve sworn a dealer said the main harness is interchangeable up untill 1988 model year being the last but maybee something got snuck in there along the way or a brainless service tech who knows lol.

well the issue with my cluster is this: i was a dumb a** i mean literally, not reading my manual clearly stating DO NOT push the trip reset button while in motion and if the gear is busted simply replace the gear. to make a long story short i busted the tach needle clear off thinking i could remove it. i interchanged the head with a 240 head and the 740 electronics but nothing works. it does work if i swap that little yellow resistor? box part with the 240 part but the speedo says 120 when im at 55 mph so it throws the whole shebang off.(od measures 100 percent though) replaced the original part on the circuit board and gave up for the time being.(mileage is currently being kept on my gps) atleast i won a 100 dollar total incompatability bet with the dealer few years back lol but regardless i need this to work. like i mentioned many sources say that the 740s can interchange yazaki and vdo clusters respectively without any mods(even the haynes says it) but i only got one cluster working and that was parted out years back:( im totally stuck here as where to go. can i mod the 240 head(240 speed sensor?) or is the flex board in need of mods on the yazaki cluster. everything works except the ac short issue and temp gauge.
oh also can i just get away with putting the yazaki head in the vdo setup? i thought i tried if memory serves me right and things are a bit diffrent.