specifically, if anyone has compared blocks.
i know astron I balance shafts have a different profile to astron II shafts.

My question is (the tp had an astron II head) so when was the astron II brought in? was it tr, tp or earlier?

http://en.wikipedia.org/wiki/Mitsubishi_Astron_engine#4G54

main answer in second gen forum for you

http://www.aussiemagna.com/forums/showthread.php?t=103842

We now have an active member running a TR/TS engine in his first gen